Arimaa/risteall vs. ChrisB
In this 2018 postal game, a horse pulled a rabbit and was then itself taken hostage. However, the hostage position fell apart because the hostage-holding camel was not adequately supported.
Diagram 1: the setups.
- 1g. An MH setup gives Gold possibilities of quickly attacking c6. On the other hand, it gives Silver the option of taking an alignment advantage by putting both horses on the other wing.
- 1s (diagram 1). Instead Silver puts his camel on the other wing, offering a game of competing attacks, but also giving himself some flexibility by placing the camel on the f-file and the horse on the g-file; the silver camel might go west while the horse defends f6.
- 2g Ha2nnnn. Gold immediately advances the a2 horse to a6, from where it could soon reach b6 if Silver does not prioritize western defense. There is no direct punishment for the horse advance, as Gold would be happy with 2s ee7swww 3g Ed2nnnn.
- 2s ee7sssw. By moving his elephant to d4, Silver restricts any western development by Gold.
- 3g Hg2n Cg1n Mb2n Ed2n.
- 3s hg7s mf7ws de8s. Both sides develop; Silver brings his camel one file closer to the a6 horse, threatening to hostage it. Such a hostage may be ineffective, however, if the western silver horse does not get to a5 to support its camel.
- 4g Ha6s ra7s Ha5s ra6s. Unable to block the silver camel from b6, Gold retreats his horse and pulls a rabbit along. Gold did not have to pull the rabbit, but is perhaps trying to justify his 2g. Had Gold advanced his elephant first, he could have begun an EMH attack and likely kept the silver camel out of the northwest. Instead, Gold has limited himself on his camel wing, as the pulled silver rabbit might impede an attack on c6. Silver currently has a development advantage.
- 4s ed4ww rf8s ra8s. Silver could aim for an attack on f3, but instead moves his elephant west, protecting his rabbit and threatening to flip the gold camel or horse.
- 5g Dc2w Ed3nw Mb3e. Gold chooses the only move that will free his camel without exposing a rabbit.
- 5s eb4s Ha4en eb3n. Silver flips the horse, intending to hostage it with his camel.
- 6g Rc1n Ec4n ra5s Hb5w. If Gold instead pushed the rabbit back to a6, it would be difficult for Silver to take a horse hostage. However, Gold is willing to allow the hostage, believing that Silver cannot hold it without his elephant nearby. The a5 square will be crucial to a horse-by-camel hostage position, as the silver camel could be pulled from b6 to b5.
- 6s eb4n me6www. This is the only move that will not allow Gold to separate his horse from the silver camel.
- 7g Ra1n Db2n De2n Hg3n. Gold moves toward a partial blockade of the silver elephant; this is a standard response when an elephant is too committed to securing a horse-by-camel hostage. The rabbit step also prevents the silver rabbit from advancing too far. If Gold can free his camel while maintaining a southwestern blockade, he might want to attack f6; the horse step anticipates this.
- 7s mb6we Ha5n de7s. The horse hostage is not good at the moment, but Silver hopes to get the b7 horse to a5, where it could support the camel and thus free the silver elephant. It might have been better to put the elephant on b4 with the fourth step. Gold could then blockade c4, but after 8g Mc3n De3nw Rc2n 8s ra4s Db3s eb4s the silver elephant is threatening to reach c4, and Gold does not have time for the pull-and-replace on b6 because of the threat to the c3 rabbit.
- 8g Rb1n Db3n Rb2n Mc3n. Gold blockades the silver elephant. Silver could unfreeze and advance his rabbit, but after 8s eb5w ra4s ea5e 9g Db4w Rb3n Rc2wn the blockade is intact and the rabbit closer to being captured.
Diagram 2: after 8s.
- 8s cd8e dd7e cc7e hb7e (diagram 2). As the silver elephant cannot escape through the southwest, Silver prepares to move it through c6, aiming to preserve the hostage.
- 9g Rh2n Cd1n De3ww. Gold brings his eastern dog west, so that he can push the silver rabbit south and still maintain the b4 blockade.
- 9s mb6n eb5ne mb7s. The silver elephant escapes through c6.
- 10g ra4s Db4w Rb3n Dc3w. Breaking the hostage immediately with 10g Ec5we mb6s Ha6e runs into 10s ec6e Hb6e ra7ss. Gold therefore threatens the rabbit.
- 10s ec6ess de6w. Silver prepares to defend the rabbit with his elephant.
Diagram 3: variation from 11s. Silver cannot defend the camel.
- 11g Ec5we mb6s Ha6e. Gold declines to capture the rabbit, as he would soon face a second horse capture threat which he could not defend against e.g. 11g Db3s ra3eex Db2n 11s ed4e Mc4en ee4w 12g Md5eess 12s ed4ee Hg4n ef4e. Gold thus breaks the hostage and threatens the silver camel, which he could capture if the silver elephant went east: 11s ed4ee Hg4n ef4e 12g Mc4se 12s Hg5w eg4n Hf5nx eg5w 13g Ec5e mb5es Ed5w (diagram 3).
- 11s ra7s rb8ws ra6s. Gold would be happy at this point to have his camel in the east, so Silver would not gain anything by flipping the gold camel to d5 and allowing it to retreat to f3. Silver advances rabbits to unfreeze his camel.
- 12g Re1n Rh1n ra5n Da4n. Even if flipped to d5, the silver camel could again take the gold horse hostage: 12g Ec5n mb5ee Ec6s 12s dd6e md5nw de6w. Gold thus pushes the rabbit back so that the camel is again frozen.
- 12s Mc4s ed4w de7s ce8s. Silver threatens to unfreeze his camel, and will be able to disturb Gold's southwestern position. Immediately unfreezing the camel would not work since it could be flipped to c4.
- 13g Db3s ra3e Ra2nn. Since a camel flip still seems not to break the hostage (e.g. 13g Ec5n mb5ee Ec6s 13s de6s dd6e md5n 14g Ec5n md6s Ec6e Rb4n 14s md5wn ec4n), Gold blockades b4, keeping his camel on c3 so that it can go east. Alternatively 13g Rb4w Db3n ra3e Cd2n prevents Silver's next move, but then the lack of pieces in front of the silver rabbit could be a liability e.g. 13s ec4e Db4e Cd3e ed4s 14g Dc4w Mc3n rb3e Db4s 14s Ce3n ed3e rc3x Ce4n ee3n.
- 13s Mc3e ec4sn Rc2n. This move delays the rabbit frame; also, the advanced gold rabbits are now starting to look in Gold's way.
An alternative approach was to block the gold camel from the east and try to advance there, using Gold's comparative weakness in the centre and east. 13s ec4es de6ss threatens to penetrate the gold lines with the dog, and the gold camel has trouble going east: if it moves to d4 it will be pushed to e5. Gold might be forced into messy tactics like 14g Mc3n rb3e Db2n Hg4w 14s hg6sss 15g Ec5n mb5ee Ec6s.
- 14g Rf1w Cd2w Md3e Rc3e. The camel steps east so that it cannot be pushed back to c3; the Rf1w step anticipates the silver elephant coming to c2 and thus creating a western goal threat.
- 14s ec4e Rb4es ed4w. Silver clears space to unfreeze his camel, and will likely give up his rabbit if Gold now frames it. Had Silver instead eyed a goal threat and moved his elephant to c2, Gold would have scrambled to defend the southwest, and the silver camel might have been freed that way. 14s ec4s Cc2e ec3s de6s 15g Rb4e Rd3w Me3w Re1w 15s Db2s ec2w rb3ws 16g Rd1w Db1w Rc1w Cd2w 16s eb2nn Hb6n mb5n could have worked for Silver, although the details are unclear.
This possibility illustrates how much a piece in front of a horse hostage can affect the position. If Silver had had nothing in front of the hostage, the hostage would have been worthless. Gold believed that the rabbit in front would make little difference, as the rabbit was vulnerable and could not itself unfreeze the camel. However, the need to control the rabbit has restricted the gold pieces, and denied Gold room to push the camel south.
- 15g Rd3n Rc3e rb3e Db2n. The rabbit is finally framed.
Diagram 4: after 15s.
- 15s ec4w rc3x Hb6n mb5n eb4n (diagram 4). Silver might want to move his elephant back to c4 after moving his camel, but Gold could undo that move and still create a new position, as a silver rabbit would be gone: 15s ec4w rc3x Hb6n mb5n eb4e 16g Ec5we mb6s Hb7s would give Gold a winning repetition fight that would soon force Silver to play a move other than ec4w Hb6n mb5n eb4e. Silver could push the gold horse to c6, but that would allow it to escape east and strengthen Gold's position e.g. 15s ec4w rc3x Hb6e mb5n eb4e 16g dd6s Hc6e dd5e Hd6s 16s Rd4e ec4e Hd5n ed4n 17g Ec5n mb6s Ec6w. Since Gold will be able to blockade c4, the elephant prepares to move through c6 again.
Comparing diagram 4 to diagram 2, the gold horse has been moved from a6 to b7, which gives Silver the option of pushing it to b8, protecting the silver camel and clearing b6 for the silver horse. On the other hand, Gold is more advanced and has captured a rabbit; the rabbit capture gives Gold a freer position as well as a material lead.
- 16g Ec5e Me3n Ed5w dd6s. Gold now wants to combine material threats with threats to disrupt the hostage pattern. The played move conveniently blockades d4 while threatening the dog: if the silver elephant goes to c6 immediately, the dog will be flipped to c4.
- 16s eb5s Da5e ra6s de6w. The hostage will be stronger if Silver can gain space on the a-file. This move incidentally threatens a dog frame.
- 17g Cc2nn ra5n Db5w. It would be difficult to prevent the silver elephant escaping via either c4 or c2; pushing the a5 rabbit back at least forces the silver camel to move before the elephant leaves, or the camel will be pulled to b5 again. Occupying c4 prevents the elephant from reaching d4 immediately.
- 17s Hb7n mb6n eb4nn. Pushing the gold horse to b8 might be the first step towards strengthening the hostage by getting the silver horse to b6 and camel to c7. But Gold is threatening to win the d5 dog in f3, and preventing this with the other two steps is tricky. Silver could have tried leaving the elephant on b4 for a move, since the gold cat would hang after 17s Hb7n mb6n hc7sw 18g dd5e Ec5e Me4s de5s, while Silver is just in time to defend the dog after 18g Me4nn dd5e Rd3w 18s Db3w eb4sse. In the latter case the gold camel might join the fight at c6 before the silver elephant returns to the centre, with a messy position which is probably good for Gold.
After the played move, Gold is clearly ahead, since he will get a material advantage worth more than the horse hostage.
- 18g dd5e Ec5e Me4s de5s. Gold threatens the silver dog. This move would not be effective were the gold horse still on b7, as the horse could then be captured in exchange for the dog.
- 18s eb6se Da5e ra6s. Silver makes a counterthreat to delay the dog capture, while again trying to gain space. 18s eb6se mb7s Hb8s would fail to 19g dd6e Ed5n Rd4n Rd3n, blocking the silver elephant from defence of the dog.
- 19g dd6e Ed5n de4e Me3n. The d6 dog is pushed east rather than west since this weakens the hostage trap.
- 19s mb7s ec5ee Rd4n. It would take Gold four steps to capture the dog and retreat both camel and horse to safety on the third rank. Silver pulls a rabbit, planning to answer the dog capture by threatening it in f6. This means leaving the horse unfrozen on b8, which will lose time if Silver later wants to threaten it, but the horse is still hostaged in a strategic sense since it probably does not have time to escape by pushing along the back rank.
This move is a mistake, however, as Gold is not obliged to capture the dog. 19s mb7s Hb8s ec5ee or 19s hc7sw mb7e Hb8s was probably better.
- 20g Cc4n ra5n Db5w Rd3n. Gold could capture the f4 dog, but wants to push the a5 rabbit back to a6 while a6 is still empty; if silver rabbits held both a6 and a5, the horse hostage would become stronger, as the silver camel could not be frozen on b5. Gold thus retakes a5, while also threatening to push the silver camel south with the elephant, possibly creating a double-threat in the west.
Diagram 5: variation from 20s.
- 20s Me4s ee5s df4nw. Silver would need three steps to save the f4 dog, and could lose the c7 horse if he used his last step to freeze the b8 horse. Silver must therefore choose between saving the dog or keeping the horse hostage. Preserving the hostage with 20s hc7s Cc5s hc6s cd7w 21g df4sx Hg4ws Me4s 21s ee5s Rd4s ee4w mb6n (diagram 5) leads to a position where neither side has a quick plan. The gold camel would now like to go back west to deal with the c5 horse, and it could be difficult for the free silver elephant to achieve anything while preventing this. Meanwhile Gold might make slow progress by bothering the hostage pattern, for instance moving the elephant to c5 or perhaps putting the dog on b6. Gold's western space advantage would be an asset in this fight.
Instead Silver chooses to save the dog. Although a single hostage would usually not be worth a dog, the camel push to b5 is the difference between Silver having a horse hostage and Gold having a camel hostage, so could be worth a dog in principle. In any case this move could be a practical mistake, as it simplifies the position when Gold is ahead.
- 21g Ed6w mb6s Ec6w Hb8s. Hb8s is the most natural fourth step, as the horse will be useful at c6.
- 21s de6w Rd4w ee4w rc8w. The rabbit push to c4 is intended to obstruct the camel hostage, but perhaps 21s de6ww cd7s was better, keeping the gold horse out of c7 and delaying the b3 dog's crossing the trap.
Diagram 6: variation from 22g. After a trade of camel for horse and cat, the silver elephant cannot defend c6.
- 22g Eb6ew hc7s Hb7e. Gold might have been tempted to play Db3ee mb5s Eb6s, which would create a one-turn camel-capture threat while also correcting the dog imbalance resulting from 9g and 10g. Silver could then capture the c5 cat and threaten a horse; capturing a horse and cat will usually make up for a camel loss, although it is not clear that Silver could actually capture a horse without suffering a further loss himself. Rather than going for such an exchange, Silver could defend his camel at little cost. After 22s Rc4s ed4w de5n, Gold does not have time to defend c3 and c6 and also take a secure camel hostage, and Silver has some annoying threats in c6 e.g. 23g Hb7s Re2ww 23s mb4ss Cc5n ec4n.
Gold thus opts not to immediately threaten the silver camel, and instead gets his b7 horse onto c7 to strengthen his control of the c6 trap. Due to the positions of the respective horses and the gold elephant, this is an unusual pull-and-replace which uses three steps to do what the opponent would have likely soon done anyway, i.e. advance the silver horse.
- 22s ed4e Rc4e Cc5s hc6s. The silver horse could be defended by a blockade on d7, but this is fairly pointless as it wants to advance to defend the camel hostage. Silver could delay a standard hostage pattern with 22s de5n Rd5e Cc5e hc6s 23g Db3ee mb5s Eb6s 23s Rc4s ed4w Ra4s mb4w, although this leaves the elephant blocking the further advance of the horse. Later in the game the silver elephant went to d3; it was probably better to do so immediately with 22s ed4s Rc4e Cc5s hc6s.
- 23g Db3ee mb5s Eb6s.
- 23s Me3e ee4s rb8ss. Silver defends the camel with a counterthreat to the gold camel. This also creates a false protection capture threat in c3 should the western silver horse or camel become unfrozen.
- 24g Hg4ww Mf3n Re2w. Gold improves his alignment by putting his camel near the g6 horse and his horse near the silver dogs. The rabbit on d2 prevents the d3 dog from being pushed back, which aids Gold's control of c3 since there will be a blockade on c4.
- 24s Dd3w ee3w dd6w cd7s. By stuffing the c6 trap, Silver unfreezes his horse and blocks the gold elephant from c5 or c6.
Diagram 7: variation from 25s.
- 25g mb4s Eb5s Re1n Rd2w. Gold could now push the camel to a3, but instead holds the hostage next to the trap. This is desirable, where the pattern can be maintained, because then the capture takes only two steps. The drawback in general is that the opponent need bring in just one more piece to free the elephant, but that is not so simple here: c4 is blockaded, and 25s ed3e Dc3e Cc4s hc5s freezes the horse and gives Gold a winning goal attack with 26g Da5e rb6n Db5n Ra4n 26s dc6s cd6w ce7sw 27g Eb4n hc4w dc5s Eb5e 27s hb4w Ra5e ha4n 28g rb7n Db6n Rb5n Ec5w (diagram 7) (or 28g Hc7e cd6e cc6x Hd7s Rc2w 28s Rb5s ha5e ra6s ce6n 29g Cc3s Rb2w Hd6n Rd5n, also winning).
Earlier in the game Gold's space advantage made it easier for Gold to fight against the horse hostage. It now strengthens the camel hostage by making it harder for Silver to advance towards c3, and giving Gold quicker threats at c6.
- 25s ed3e Rd4s He4w ee3n. Seeing few viable moves, Silver offers a camel trade. After 26g Rh3nw Mf4s Rc2e, however, Gold's camel would be safe, and Silver would have little choice but to reverse his 25s to save his own camel.
- 26g Rd3e Dc3e mb3ex Eb4s. But Gold will gladly take the camel trade, as tactics then favor him.
- 26s Mf4n ee4e Mf5nx ef4n. Keeping the c5 horse safe takes two steps. Silver could try 26s rb6s dc6w Mf4n ee4e, but then after 27g Hd4e de5n He4n Mf5e it seems Gold will lose at most a horse in exchange for the camel.
- 27g Eb3nn Cc4w Re3n. Gold advances a rabbit to e4 so that the gold horse cannot be pushed to c4, where it would block the capture of the c5 horse.
- 27s de5n Rd5e hc5e ef5s. This is a mistake, as b6 should have been blockaded. However, after 27s de5n Rd5e hc5e ra7e both the horse and the c6 trap remain vulnerable, for instance 28g Eb5ew hd5w Hd4n 28s hc5se Cb4e dc6s 29g Eb5s Cc4sw Eb4e 29s rb6ss cd6ww 30g Da5e cb6e Db5n Ra4n.
The alternative was to attack in the east with 27s hg6sss ef5s. Then Gold would probably not want to capture the horse immediately, but would still win it after 28g hc5s Eb5e Dd3e. Gold would have to defend for a few moves, but should be able to do so comfortably.
- 28g Eb5e Da5e rb6n Db5n. Gold's attack is crushing, as captures in c6 will come with very quick goal threats.
- 28s hg6sss ce7w. The silver elephant could probably defend c6 in time to prevent a short-term goal, but Silver's position would be hopeless, as the gold elephant could rotate out and dominate the board. Silver thus counterattacks f3; Gold can win this race, but there is always a chance that one with a winning position will miscalculate. An apparently hopeless counterattack may thus be better than a hopeless defense.
- 29g cd7e Hc7ew cd6n dc6x.
- 29s ef4sw Rf2nx cd7s. By capturing the f2 rabbit and moving his elephant to e3, Silver makes way for a goal threat on the f-file. To protect the d5 horse, Silver steps the d7 cat to d6; Gold will not have time to capture both the cat and horse.
- 30g Db6e Ra4nen. Gold creates a one-turn goal threat, to stay ahead of any goal attack by Silver.
- 30s cd6nnw ce7w.
- 31g cc8e Hc7n Dc6n.
- 31s rf7sss ra6s.
- 32g Dc7s rb7e Rb6nn. Gold wins.