Six developers signed up for the 2008 Computer Championship, including four of the eight participants from the 2007 tournament. The two new bots, Opfor and sharp, have generated excitement with some strong games in the weeks leading up to the event. In addition, the top three bots from last year are all returning, meaning this tournament should produce many interesting, competitive games. Bomb has won all four previous championships, with an impressive record of 22-2, losing one game to Clueless in each of 2005 and 2006. Will this finally be the year that a different bot wins the championship? It will certainly be exciting to find out!

Correction from previous report: The winner of the Computer Championship does not automatically participate in the Arimaa Challenge. One of the top two finishers will represent the computers in the Arimaa Challenge, depending upon which performs better against human opponents in the two weeks leading up to March 16.

Round 1

Bomb vs. Zombie

The game opened with a dual-lone elephant attack. Bomb pulled a silver camel offside, while Zombie pushed a goal dog into the north. With its 5th move, Zombie’s elephant released the dog to attempt a rescue of its camel. When Bomb continued its pursuit of the camel, the silver horses converged to freeze the offside gold dog. With its 8th move, Zombie pushed a cat onto the f3 trap to possibly delay the capture of its camel. Bomb, however, was willing to allow its cat to fall into the trap in the process of capturing the camel. Zombie then trapped the gold dog with its horse tandem, leaving gold with an extra camel in exchange for a dog and a cat. Based upon the developer's comments, each bot considered itself to be ahead at this point.

On move 11, Bomb made the interesting decision to sacrifice its f1 rabbit, which Zombie accepted. The rabbit-sacrifice may have been intended to build up attacking threats while the silver elephant was briefly on the f2 square. Zombie appeared to miss a good opportunity to retreat one step north with its horse on move 13, pulling a rabbit instead with its fourth step. By move 18, Bomb had arranged its pieces very powerfully in the southwest corner, holding the silver horse hostage with its camel, while blocking out the b4 square with a frozen silver rabbit. With the silver elephant tied to the defense of its horse, the gold elephant was free to move east and take a wandering silver horse hostage on move 19. Unable to protect both hostage horses, Zombie exchanged horse for rabbit on the next move. Bomb now had an overwhelming positional and material advantage and pressed the advantage further with an Elephant + Horse attack against the northeast trap. With the strongest silver pieces standing in the southwest, Zombie could not stop the subsequent rabbit advance in the east and gold scored the goal on move 28.

Loc vs. Clueless

The tactical play started early as Loc launched an Elephant + Horse attack in the northeast while Clueless had threats against the f2 gold dog and the potential for an offside camel push after 4 moves. Loc continued his E+H attack by pushing the camel away while Clueless launched his own Elephant + Horse attack in the southeast. The two sides exchanged dogs before Loc moved west to attack the northwest trap. There was another exchange on move 9 as each eastern horse trapped a rabbit.

Loc made a curious move on move 10 by moving a cat to e2 when no gold pieces had been threatened there Clueless immediately captured the cat, but brought the elephant to f2 in the process. With the silver elephant temporarily decentralized, Loc took control of the northwest trap, guaranteeing a piece capture on the following move. Clueless captured the f1 rabbit while recentralizing the elephant to e3. Loc captured the exposed c7 cat, repositioning the elephant to c5. With the c7 and d6 squares vacant, Clueless used two steps to re-protect the c6 trap and used the other two to position for another rabbit capture in the southeast. After capturing the gold rabbit in the southeast, Clueless had a powerful strategic advantage in the wide-open eastern side: Gold had only a g8 horse and h1 rabbit on that half! Clueless began to roll its rabbits forward on move 14 and then won on move 17 with a nice elephant sacrifice.

Opfor vs. sharp

Sharp got into trouble early when its camel advanced from a7 to a5 on silver’s opening move. Opfor started to push the camel south with its elephant, but then lost the advantage when the silver elephant flipped the gold camel to d4 on move 4. Opfor advanced a cat to c4 on move 5 so that the camel could flee east but sharp continued to chase the camel, and pushed it north to f5. Opfor advanced its b3 horse one step north on the 6th move, allowing the silver camel to be pushed to a3 with a clear path to the trap. However, this left the c4 cat unprotected so the silver elephant returned to both trap the cat in c3 and protect the silver camel. On the next move the gold camel still stood on f5, so the silver elephant returned east to initiate an exchange of camels.

On move 10, Opfor moved the gold elephant to b6 to threaten a silver horse and sharp retaliated by counter-threatening a gold horse in the southwest. This was a tactical error by sharp, as Opfor was able to capture a horse and rabbit for a horse during the exchange. The two lone elephants then repositioned around the same enemy traps for a new series of piece exchanges. Again, sharp made a tactical error and Opfor captured 2 silver rabbits versus one gold rabbit by sharp during the second sequence of captures. An exchange of dogs on move 18 further opened space on the western side of the board.

Sharp advanced its rabbits on the eastern front on the 19th move despite not having any strong pieces to support them. Opfor then created a double-threat, threatening both a western silver cat and one of the recklessly brave eastern rabbits. Sharp didn’t protect either piece and Opfor chose to trap the cat in c6. Despite possessing only 1 silver rabbit versus 3 gold rabbits on the western half of the board, the silver side took the initiative with a rabbit advance to a2 (its only piece on the western half other than the elephant!) Gold still had the material advantage of 2 rabbits for a cat but silver had a rabbit on the 7th rank on each side of the board, as Opfor had not yet gotten around to capturing the unprotected rabbit on the eastern front. Though Opfor was winning, it needed to play carefully to prevent the advanced rabbits from scoring. Instead, Opfor began a premature rabbit advance on the western wing without first solidifying its goal defence. With its 24th move, sharp began a forced series of moves that should have captured a gold rabbit and cat. On move 26, Opfor correctly moved its cat to c2 to (just barely) hold the position on both wings. The mistake was stepping north with the a1 rabbit – that decision saved the gold cat on c2 but allowed silver to force a goal-in-three with its response. With the remarkable victory, sharp moves on to play Clueless in round 2.

Round 2

Clueless vs. sharp

Sharp began the game with an elephant and horse advance, plus one of its dogs was pushed offside on move 5. The three silver pieces quickly converged on the c3 trap, but sharp couldn’t prevent its dog from being framed on the next move. With the silver elephant tied down in the southwest, Clueless then began to advance a horse into the northeast. That was a rather bold decision, as the quadrant was defended by a silver camel! The gold camel then followed north to save its ally from danger. Sharp took the gold horse hostage while the gold camel protected it from f5. On move 10, sharp correctly calculated that it could abandon its framed dog to trap the horse hostage.

During the next few moves Clueless pushed a silver cat offside while sharp pulled a rabbit north along the a-file. Sharp then sent a horse into the southwest to protect the cat, and it turned into an Elephant + Horse attack. Clueless tried to bring its camel over to the west side, but sharp abandoned its advanced horse to push the camel into the north. Unable to save its camel, Clueless settled for trapping the silver horse into c3. After 22 moves silver had an extra rabbit plus it had won two exchanges, resulting in a camel for a dog advantage with a horse removed from each side. Clueless cut the material deficit by move 25, having won 2 silver cats in exchange for a gold cat. On move 26 Clueless advanced its elephant onto the lightly defended 7th rank, but sharp was pushing towards a goal in the southeast. With silver’s rabbit getting closer to a goal, Clueless responded by clearing out the southwest and advancing its own rabbit up the b-file. Sharp had the lead in the rabbit race the whole way, however, and was able to score on move 30. Sharp has been the story of the tournament so far with a perfect 2-0 record. It faces a huge challenge in round 3 against the four-time champion Bomb.

Bomb vs. Loc

Loc built an early positional lead against the heavily-favored Bomb, taking a gold camel hostage on move 5 at the h7 square. Bomb made a nice follow-up, putting his dog on h5 so that the camel could retreat back to h7 if the elephant tried to pull it to h6. From that point onward, Bomb built a powerful positional advantage while the silver elephant was standing on h6. First the gold horse took control of the important b6 square on move 7, then the elephant pushed a silver dog into mortal danger at g4. Loc countered with a threat against the c2 dog, but Bomb was able to defend it easily while capturing the silver dog two moves later.

Loc tried to create counter-chances by manoeuvring its strong pieces in the northeast but Bomb parried all of the attempts. Still maintaining full control over the c6 trap, Bomb was able to capture a silver rabbit on move 15. Loc fought to regain control of the northwest trap, sending a camel and rabbit to re-claim it from the gold horse and dog. When the gold elephant threatened to push the silver camel into the southwest trap the advanced silver horse moved to c2 to protect it. However, the lone horse was no match for the gold elephant, as Bomb was able to freeze three key silver pieces while threatening both the horse and camel on move 20. With no tactical miracle available, Loc succumbed to a horse capture then scattered its other pieces to avoid further losses. With the silver defenders scattered away from the northwest, Bomb then used its horses and camel to dominate the northeast, capturing another silver rabbit in the process. Loc was never able to regain full control of any more traps for the rest of the game. After distracting the silver defenders with a rabbit advance in the west, Bomb was able to create a hole up the middle, through which a rabbit darted to victory on move 36.

Zombie vs Opfor

The game began with a Dual Lone Elephant opening, albeit a very tactically sharp one. On move 6 Zombie had the option to exchange cats, and though its first two steps indicated it would accept the trade, it decided to protect its c3 cat in the end. In response, Opfor pushed the gold camel northwest and held it hostage at a6. Zombie countered with a silver camel push to d5, and then followed-up with a horse advance to c5 on the next move. After several moves of pushing and pulling, Zombie managed to capture the camel, at the cost of a cat. Zombie also threatened to capture a horse on move 18, but Opfor was able to rescue it with a rabbit. Zombie did manage to capture the advanced silver rabbit two moves later, but Opfor’s horse managed to escape to the safety of the a-file.

With the gold elephant still protecting the camel in the northwest, Opfor launched a Horse + Cat attack in the southeast. The attack was neutralized by a gold horse, then abandoned when the cat found itself buried at h2. For several moves afterwards, Zombie slowly advanced its forces northward, including a rabbit while Opfor moved pieces over to block the advance. The silver horses moved into the southwest quadrant to challenge a trap while gold built some pressure in the northwest. On move 35 the two armies exchanged rabbits but then complications arose as each side later attempted to freeze and threaten various pieces. The situation became even more complex after silver’s 39th move as three gold pieces faced long-term capture threats and the gold elephant stood on c3 surrounded by three silver pieces. However, Zombie quickly built up threats of its own by first advancing rabbits up the middle of the board and then removing the f7 silver rabbit from play. On move 44, the gold horse advanced to f7 and silver could not prevent the g6 gold rabbit from scoring on the next move.

Round 3

Zombie vs. Clueless

Zombie opened the game with a lone elephant attack up the middle, and an unorthodox rabbit advance up the a-file. Clueless took the rabbit hostage and it appeared to be a serious liability for the gold side. After it was framed by three silver pieces, Zombie sent its camel north to help free it on move 8. Silver’s best practical chance may have been a rabbit flip from c6 to e6, or possibly an attempt at a camel hostage. As the game played out, the rabbit became freed and the attacking gold camel became semi-buried at a7 (though not at any apparent risk of a complete blockade). Zombie built a powerful positional advantage on the 14th move, freezing the silver horse on b5 while forcing the silver elephant to d6 to prevent immediate material loss. When the silver horse was pushed into danger at c4 on move 15, Clueless abandoned the northwest trap and moved its elephant south to save the horse. Zombie had an interesting decision to make on move 16 as the d7 silver dog was vulnerable to capture, but doing so would necessarily place the camel on the dangerous d6 square. Clueless would have had some good compensation for its lost dog had it pushed the gold camel to e6 – instead, the camel was pushed to d7 and Zombie held the advantage.

The next several moves had recurring tactical themes. The silver elephant would attempt to disrupt the gold position in the north, then advance to d4 to save the endangered silver horse, then return north once again. Zombie was finally able to capture a silver cat on move 22 when the silver elephant stood on d4. The two sides then exchanged rabbits on the next move. With gold goal threats looming, Clueless shifted defenders west to close up goal defence gaps and the silver elephant took the gold camel hostage. By move 29, each side had a horse in mortal danger. Clueless captured a gold horse in the northeast and also threatened to capture a camel on the next move. Rather than capture the silver horse, Zombie captured a rabbit instead to create a goal threat. On move 32, with its camel still threatened, Zombie once again delayed the capture with another goal threat. Finally on move 33, two strong hanging pieces were finally captured as Zombie captured a silver horse and Clueless captured the gold camel in return. At that point, Clueless had an extra camel versus an extra dog, cat and rabbit for Zombie, not to mention two dangerous gold rabbits on the 7th rank. Zombie delivered a powerful blow on move 37, threatening both goal-in-one and a camel capture in the northwest. After losing the camel, Clueless was able to defend for several more moves until Zombie was able to force a goal on the 44th move.

Loc vs. Opfor

In a dual lone elephant opening Opfor pulled out a cat while Loc worked on getting a horse hostage. After getting the silver horse down to g4 on move 11 Loc gave up on taking the horse hostage and decided to try and save the cat while also making a series of threats against Opfor's pieces around f6. Opfor replied by starting an EH attack against f3. On move move 14 Loc ran out of threats at the f6 trap. Loc then brought the elephant back to defend the f3 trap where Opfor was threatening a horse and dog. Opfor then captured the cat and brought its camel out to f5 without first retreating a cat that had been moved down to f4 earlier. This allowed Loc to get the cat over to d3 threatening to trap it. Opfor decided to defend by bringing the camel over to c4 and both defend the cat while also pushing a gold horse, threatening to trap it in c6. Loc then pulled the cat back to e3 and brought its elephant over threatening to trap the camel. Opfor defended by bringing a dog down to b3. Opfor was able to stop any capture in c3 with the camel, dog and cat and on move 20 Loc decided to bring the elephant back to e3 again. Opfor then once again threatened to take a horse with the camel on c4 and horse on c5. Loc brought the elephant back to c4 pushing the camel to d4. This time the cat was already frozen by the gold camel and so this time Loc threatened the camel, dog and cat. With no way for Opfor to defend c3 using minor pieces, Opfor in the next two moves rotated its elephant over to d3 moving its cat to e3. Loc then worked to take the dog hostage and push the camel over to the east but this gave Opfor enough time to trap a dog, cat and rabbit at f3 with its horse. With a fair amount of piece shuffling and threats on both bots camel and horses by move 41 Opfor had captured another 3 rabbits for a cat. Then Loc abandoned the f3 trap with its elephant to threaten a dog and rabbit as well as develop a goal threat. This allowed allowed Opfor to take a horse at f3. Loc responded by capturing the rabbit and keeping the threat on the dog. But Opfor was able to bring its elephant across to threaten Loc's camel and horse on the west side. Loc decided to bring its elephant back to d3 abandoning the threats in order to prevent the camel loss. Opfor then froze all of Loc's east side pieces and threatened a goal in two which Loc did not defend against. This allowed Opfor to bring a rabbit down the g-file for goal on move 45. (BH)

sharp vs. Bomb

Sharp opened the game with a very aggressive Elephant + Camel attack in the northeast. Bomb made a smart, straight-forward decision to push the camel south to g7 and hold it hostage there. Sharp tried to capture a horse in the southeast as compensation, but Bomb was well positioned to ward off the threat. When Bomb sent its 2 horses into the southwest quadrant, a gold horse neutralized them while the other horse dragged a silver dog into the southeast. Rather than protect the dog with a horse (which would have led to a horse + dog for camel exchange), Bomb sent its camel into the southwest to aid the silver horses on move 11. Because the gold elephant was tied to the camel hostage, the gold pieces had to scatter pieces away from the M+H+H attack. Sharp was able to evade capture until move 15, when it finally gave up a horse for a dog. After framing a dog on f6, Bomb sent its camel into the southeast to initiate a gold cat & rabbit for silver dog exchange. Bomb still maintained a small material advantage but more importantly it now completely controlled the southeast quadrant and had the opportunity to begin a powerful rabbit advance. Sharp held out for a few moves, but using nothing but rabbits to stop the silver camel + rabbit tandem, gold could do little to prevent the loss. On move 22 Bomb marched to victory and, as a result, took sole possession of first place with a 3-0 record and earned a fourth round bye.

Round 4

sharp vs. Zombie

Sharp opened by advancing its elephant and then one horse to b5 and the other to f4. Zombie responded by taking the west horse hostage with the silver elephant on c5 and then trying to get a hold of the other horse with its camel. But sharp brought its elephant back to threaten the silver camel. Zombie was able to advance a dog to unfreeze the camel. Leading to an exchange of the camel and dog for both of silver's horses and a cat by move 10. Zombie then worked to push out one of sharp's dogs to e4 while bringing a h-file rabbit to f4 and threatening the gold camel on f2. Sharp brought the gold elephant back from c5 to unfreeze the dog, pushing the rabbit back and putting the dog on f4. Rather than pursuing the dog with the elephant Zombie advanced a rabbit to a5 and put a horse on f6. Sharp moved to cover f6 by placing its elephant on d6. Zombie then left the fight on the east switching its elephant to the west and began to threaten pieces around c3. This led to sharp capturing a rabbit and horse for a rabbit and dog. Zombie was also able to advance the forward a-file rabbit to a3 giving it a goal threat at the end of the series of captures.

At 17w sharp brought its elephant over to b4 to defend the goal threat. After pulling the silver rabbit back to a4 on 18w sharp decided to send its dog to h7 on move 19. Zombie responded by bringing his horse across from d6 and freezing the dog. Sharp then prepared to bring its camel up to support and pulled the a4 rabbit to b4. At this point on move 20b, due to a bug in the bot tournament control script Zombie timed out.
After investigation into the cause of the problem it was decided by the tournament director Ned Bent and tournament coordinator Omar Syed to restart the game from move 20b. After the restart, Zombie pulled the dog out to h6 but also advanced its cat to f5 allowing sharp to trade dog for cat. Sharp then worked with its camel around f6 eventually getting a dog back to f3 to capture on move 27. In the next few moves Zombie captured a rabbit in c3 and worked its elephant over to d3 to threaten sharp's camel. Sharp in that time captured another rabbit in f3 and advanced the camel back to f5. Also creating a goal threat with a rabbit on g5.

This started a dance around f6 by the gold camel and silver elephant ending on move 34b with Zombie capturing the camel and then sharp capturing the advanced rabbit at c3. Leaving Zombie with the elephant, horse, cat and 5 rabbits and sharp with the elephant, cat and 6 rabbits. Zombie then threatened sharp's advanced rabbit with the horse and brought the elephant across to the west to protect its advanced west rabbit. Sharp protected its rabbit with the elephant and threatened the horse while at the same time pulling the rabbit toward the c3 trap with the cat. Zombie abandoned the rabbit to protect the horse and trap a gold rabbit in f3. But then lost the horse when it tried to threaten the cat with its elephant. Sharp was able to stop Zombie from taking the cat after it trapped the horse by creating a goal threat. Then on move 42b forced Zombie was forced to sacrifice its elephant to stop another threat and finally sharp sent a rabbit to goal on move 44. (BH)

Opfor vs. Clueless

This must-win game for both bots opened with a Dual Lone Elephant opening, with the gold elephant moving towards the northeast quadrant and the silver elephant towards the south central region. Clueless got the early advantage when it pushed a gold rabbit offside while Opfor shuffled its pieces around somewhat aimlessly in the corner. Clueless captured the rabbit on move 9 and gained a further advantage when it pushed the gold dog to g7 with the gold elephant poorly placed at g6. The silver camel pulled the gold dog away to threaten it in the west. When the gold elephant headed northwest to the f7 square to help the dog the silver pieces created a wall which cut off the elephant and introducing the real possibility of an elephant blockade. Though the gold elephant did manage to escape through the east side, the gold dog was doomed in the northwest quadrant. With a large material advantage, and with the gold elephant far away from the action, the silver camel hunted for another victim in the south.

From moves 14 to 20, Clueless repeatedly tried to pull a gold piece offside, but each time Opfor would bring it to safety. Finally, on move 21 the silver camel pushed a gold dog to e5 but Opfor produced a strong counter-response, freezing both the camel and horse two steps away from the f3 trap. Clueless saved its camel and Opfor won an exchange, capturing a horse for a dog. On move 27, Clueless pushed a gold horse north to d4 with its elephant. When Opfor responded with a threat to the silver camel, the silver elephant had to release the horse. Opfor held the camel hostage on the g4 square while a gold horse charged north to generate more threats. When a gold rabbit marched forward to aid the attacking horse, Clueless sent its elephant north to threaten the invading horse and free the silver camel hostage on the same move. That set up a sequence of moves where Clueless could have sacrificed silver cat and camel for gold rabbit and horse. After the exchange of silver cat for gold rabbit, Clueless had a long think and decided to save the camel in the south. That allowed Opfor to capture the silver f7 rabbit, leaving the position unclear: Opfor had the positional advantage with a high camel hostage, strong advanced horse and mobile rabbit on the h-file while Clueless had the material advantage of 2 dogs and a rabbit for a horse and cat.

Opfor made a strong 36th move that threatened the camel in the f6 trap, while blocking out the elephant from the northeast. Clueless couldn’t put 2 pieces near f6 to secure the trap, so it came up with an interesting gambit instead: it placed a rabbit on f5 to protect the camel and if the gold elephant captured the rabbit then the silver camel would be able to escape from the hostage situation. Opfor declined the gambit rabbit, pushing the hostage camel back to g4 instead – however, by stepping north with its horse it allowed a dog to occupy the strong defensive g6 square. When Clueless added a third defender to the trap, Opfor made a couple of indecisive moves that left the position unclear. After much play on the eastern front, Opfor opened up the western front with a camel advance to b5. The silver elephant chased the camel, and after a few moves of manoeuvring an exchange of camels occurred on moves 43s and 44g.

The action shifted back to the east as Clueless first protected its advanced g4 rabbit then moved north to take a horse hostage on g7. After 46 moves the game was roughly even, though silver likely had a small advantage due to the gold horse hostage with the second gold horse on the same side of the board. Clueless advanced its horse to d3 on move 47, and Opfor retreated its elephant south to set up a likely horse exchange. Surprisingly, however, Clueless captured the h6 rabbit rather than prepare for a horse capture on the following move. Even more shocking, Clueless then left a dog exposed to capture on the f6 square on its 49th move. Opfor captured the dog, and then after Clueless pushed a horse hostage to h6, Opfor captured the second dog and protected the horse hostage simultaneously. Having just lost both dogs, Clueless sent a silver cat to c4 to protect the endangered horse. Opfor then used its free horse to capture the vulnerable silver rabbit on f4 – from a roughly equal position a few moves earlier, Opfor had won 2 dogs for free and now had a commanding lead. To protect its horse from being pushed into f3, Clueless advanced a rabbit all the way to the c3 square. Opfor trapped the rabbit two moves later, then began a rabbit advance of its own up the g-file. The gold rabbit scored on move 56, setting up a Bomb-Opfor matchup in round 5, while Clueless was eliminated from the tournament with its 3rd loss.

Round 5

Opfor vs. Bomb

Bomb played aggressively in the opening, grabbing the g3 square for its horse on move 4. When the gold camel occupied f3 on the next move, the silver elephant arrived to push the camel north. Opfor then brought its elephant home, and the silver horse was framed on f3 by the elephant, camel and four-piece blockade in the south. Bomb immediately counter-attacked in the southwest, using its other horse to try to pull a gold dog offside. After two attempts, Opfor froze the new invader with its elephant. That gave Bomb an opportunity to escape the horse frame and push the gold camel north to g4. Bomb had the opportunity to give up its horse for a cat plus attacking chances, but instead pushed the gold camel north and allowed an exchange of 2 silver horses for a gold camel.

After the first 3 pieces were removed from the board, all the remaining pieces stood on their own side of the board. During the next phase of play it was Opfor who invaded into Bomb’s territory. When Bomb threatened to frame a dog on c6, Opfor sent a horse up the east side to pull a cat. Bomb released the dog and moved the silver elephant east to challenge the horse. Opfor then pushed the silver camel west to b7, threatening to take over the northwest trap. Bomb once again allowed a two for one piece trade, this time giving up a silver cat and dog for a gold horse on moves 16 and 17. After this trade, Opfor had a comfortable material advantage of horse, dog and cat for camel. With a depleted board, Bomb first chased a gold dog up to d8 then moved the camel down south along the b-file. The gold elephant chased the silver camel around and then trapped a rabbit after the camel fled.

After the silver camel took the gold dog hostage on b7 on move 23, the gold elephant marched north of the c6 trap to free the dog and threaten the silver camel once again. The silver elephant was threatening a gold dog, so Bomb advanced a rabbit to d6 to defend the camel. When Opfor intensified the pressure around the trap, Bomb decided to return its elephant to c5 to secure the zone. Opfor immediately switched quadrants, commencing an Elephant + Dog attack in the northeast. When Opfor advanced a rabbit up the h-file on move 32, it broke the resistance of the silver side. Opfor won 2 rabbits for a cat, and after Bomb shifted more defenders to the east the gold dog trapped another rabbit in the northwest, opening a path for another gold rabbit. Bomb did not have the means to deal with two rabbit threats simultaneously, and Opfor won on move 37. Bomb will try to avenge its first loss when these two bots meet again tomorrow for a round 6 re-match.

Zombie vs. sharp

Zombie opened the game with very aggressively by first launching an Elephant + Horse Attack against the northwest trap, quickly followed by a gold camel invasion in the east. While the silver elephant was occupied with the gold horse on b6, the camel brazenly marched to f5 and pushed a silver horse south move 6. After sharp’s camel advanced to g3 to protect its horse, Zombie introduced complications with a wild 7th move, leaving both a cat and horse unprotected while moving its elephant onto the f6 trap to threaten a silver dog. Sharp exchanged its dog for the f2 gold cat, but found both its horse and camel threaten by the gold pieces on move 8. Unwilling to exchange the hostage gold horse for the silver camel, sharp instead threatened the gold camel in the northeast. After Zombie protected its camel, the silver elephant return to the northwest to again hold the gold horse hostage. On move 11, Zombie won a free cat in the northeast, but sharp built up a strong position in the southeast in response. With both gold horses threatened on move 12, Zombie attempted to save the b6 horse, defending c5 with a gold rabbit, leaving the g3 horse exposed to capture. Sharp pushed the c5 rabbit south, once again threatening both gold horses.

Destined to lose one of its horses or a camel, Zombie simply lost a horse on move 14 but followed with a goal threat in the northeast on move 15. Sharp was able to defend against goal with a wall of rabbits, and also threatened to push the gold camel into the northwest trap. The gold elephant counter-attacked against the southeast, trying to threaten multiple silver pieces in exchange for its camel. After some highly complex tactical play, Zombie won the exchange of camel for horse, but sharp gained a strong rabbit threat in return on move 22. Threatened with hanging pieces on both halves of the board, including a silver camel on g4, sharp used a rabbit threat and delaying tactics over a ten-move stretch to avoid further material losses. Suddenly, on move 32 a gold rabbit darted to the d7 square with no silver defender on d8 and most of the strong silver pieces in the south. As an added bonus for Zombie, the gold rabbit that had created the earlier goal threat on move 15 was also standing on at g7. The ensuing endgame was highly entertaining and instructive, and would certainly make a good endgame study for an eager analyst. Though gold appeared to have a forced win, Zombie’s advantage slipped away due to inaccurate play.

Sharp defended its position rather aggressively, actually advancing on of its defending rabbits forward on moves 34 and 35. Zombie created a strong threat on move 36, placing its elephant on f7 where it was in a position to assist both advanced gold rabbits. With its outlandish 36th move, sharp used two steps to counter-attack in the southeast and two steps in the north: it offered a cat sacrifice, but the cat sacrifice couldn’t be accepted without seriously delaying the gold goal threats (in fact, had the cat been taken the silver elephant could have retreated north to threaten both advanced gold rabbits). Though Zombie apparently could have built a long-term positional advantage by capturing the cat, instead it once again went for goal, this time with its rabbits placed on d7 and e6 and elephant still standing on f7. Sharp found the best possible defensive steps with its 37th move, retreating the camel north and preventing the e7 silver rabbit from being pulled east. By move 39, Zombie’s attacking pieces became poorly co-ordinated, and it began to make four-step moves that sharp could reverse with two steps. By move 43, sharp had not only miraculously survived, but it trapped one of the advanced gold rabbits and marched a second silver rabbit all the way to gold’s 2nd rank. Sharp completed the comeback on move 45, clearing a path for the rabbit to advance to c1. With the loss, Zombie finishes 4th in the tournament while sharp earns a well-deserved Round 6 bye.

Round 6

Bomb vs. Opfor

Opfor assaulted the southwest with an Elephant + Horse attack on move 4. Bomb’s elephant retreat to c4 to defend, dragging the gold camel behind it to c5. Opfor then had second thoughts about the attack, withdrawing its horse to b4. Bomb actually threw the horse back into the attack at c3, but it ran even further away on the next move to b5. Bomb flipped the camel onto the c3 square on move 7, and it turned into an E+M+D attack for silver. With many powerful pieces tied down in the southwest, Opfor raided the southeast and pulled a gold dog straight north to g6 with a horse. Bomb sent its camel north to rescue the dog, and by move 14 the gold pieces had turned into attackers in the northeast quadrant. When the gold camel pushed the silver horse west to e7 on move 15, Opfor decided to scatter its pieces away from the trap. Having secured the northeast trap, Bomb passed up an opportunity to capture a cat in order to dominate the northwest trap with a Camel + Horse attack on move 17. With much of its strength still bogged down in the southwest, Opfor defended the c6 trap with a cat and rabbit. By move 22, Bomb had passed up two more opportunities to capture pieces, always building the pressure with piece advances instead. Opfor then blundered in a bleak position, allowing goal-in-two with its 22nd move.

Bomb’s victory was the first no-capture game of the tournament and, more importantly, Opfor’s 3rd loss eliminated Bomb’s nemesis from the tournament. The two remaining bots, Sharp and Bomb, each have a 4-1 record and in effect will play a best-of-three series to determine the 2008 Computer Champion. Opfor finishes 3rd in its debut tournament, and in round 5 became only the second bot to ever defeat Bomb in a Computer Championship.

Round 7

sharp vs. Bomb

As has been one of its trademarks throughout the tournament, sharp opened the game with an aggressive camel incursion into the north. With its gold camel and elephant poorly placed on b7 and b6, respectively, sharp made an ill-advised horse advance to f5. Bomb’s elephant easily trapped the horse in f6, then returned to the northwest where sharp’s attackers had accomplished nothing other than a rabbit pull to b7. Sharp almost captured a silver rabbit in the southwest on move 10 but, with the gold elephant and camel stuck in the northwest, Bomb was able to send a horse to d3 to save the rabbit. A few moves later Bomb abandoned the rabbit to launch a double horse attack against the southeast. On moves 17 and 18, the two sides exchange cat and dog for cat and dog still leaving Bomb with the material advantage of horse for rabbit. Bomb effectively ended the struggle by capturing a second gold horse for free on move 24. Bomb captured one piece after another until sharp was reduced to an elephant and 8 rabbits on move 33. Sharp put up a stubborn defence, however, and Bomb had to wait until move 41 to score the goal. Unless sharp can win the final two games of the tournament, Bomb will win its fifth consecutive Computer Championship.

Round 8

Bomb vs. sharp

Sharp opened the game with an opportunity for an Elephant + Horse Attack in the southeast. However, when sharp faced the opportunity to capture a gold horse, dog and rabbit in exchange for silver camel and horse, it willing accepted the deal. Soon thereafter, on move 10, sharp had its elephant blockaded on the e1 square. With the silver camel already removed from play, Bomb used its elephant to hold the blockade while a gold camel and horse completed dominated the middle of the board. After capturing several silver pieces in exchange for a gold rabbit, Bomb advanced a gold rabbit to h6 on move 26. Even though sharp could have easily prevented goal for a few moves, it did nothing to stop the rabbit from scoring on move 27.

Tournament Summary

Bomb won its fifth consecutive Computer Championship, winning all three games against sharp, including the final two deciding rounds. Other than its loss against Opfor, Bomb dominated nearly every game from start to finish. However, the rest of the field is certainly catching up to Bomb and it no longer seems as invincible as it did for so many years. The games played between the 2nd to 5th place finishers were generally well-played, often instructive, and unpredictable with back and forth momentum shifts throughout. The two new bots impressed with their potential and Zombie and Clueless might leapfrog ahead of the others next year with a bit of work. All in all, the championship was very entertaining and everyone is looking forward to an even stronger tournament in 2009.

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