Arimaa/Attacking/Attacks Against a Camel Trap
When a camel is decentralized, the opponent might attack either trap. The trap not defended by the camel could be vulnerable, but the trap defended by the camel might be a good target also, as an elephant prefers to be near the enemy camel. If the enemy elephant is forced to defend its camel trap, and the attacker's camel is elsewhere, that camel will be the strongest free piece. If the defending camel took a strong hostage, however, such an attack could backfire badly; the attacking elephant could be stuck defending the hostage while the enemy elephant was free. Such attacks are sharp, and the whole board must be considered.
It is easier to attack against a camel which is not supported by a friendly horse. Without a supporting horse, a camel may have trouble holding a key square (and potentially keeping a hostage): a weak piece in front could be pulled away by any piece stronger than itself, and then the camel could be vulnerable to the elephant. With this in mind, such attacks are commonly employed against setups which place the camel on one wing and both horses on the other.
Eventually, the defending camel could be at risk of capture. An attacker might push the defending camel toward his home trap and thereby create threats in both traps. That could be a strong move, but it could also be risky if it decentralized the elephant in enemy territory.
Boo vs. chessandgo
Before 2g: Silver attempts to exploit Gold's setup.
This game was played in the 2013 Arimaa World Championship. Gold used an HH setup; Silver then set up with his camel directly facing Gold's horses, and his dogs far away from Gold's horses. In fact, the silver dogs face the gold camel, which would waste its strength by fighting dogs. The silver elephant begins on f7, meaning that Silver intends to first advance in the east, though there is also potential for a strong silver attack in the west. Gold has no clear prospect for an attack on c6 or f6, as Silver is likely to get a strong hostage if the gold camel advances in the east or a gold horse advances in the west.
Before 6g: Silver prepares an eastern attack.
- 6g Ed6s cd7s Ed5e cd6s. Gold pulls a silver cat, hoping to get a capture threat while also bringing his elephant closer to the coming fight. Given what follows, the cat pull was probably a mistake.
- 6s De3w ee4s dg6s rg8s. Silver moves toward a multi-piece attack on the f3 trap, to which Gold must now add a defender. The gold camel could step to g3, but would then risk being pushed to g4 by the silver elephant, which could move through the trap as soon as a silver piece reached f4.
- 7g cd5s Ee5w Mg2n Cf2n. The gold cat in f3 delays Silver's attack. Gold hopes to capture the silver cat before Silver's attack is far advanced.
- 7s hf5s hb6ss mb7s. The silver horse threatens to push the gold cat to g2 and occupy f2, or flip the gold cat to f5.
Before 10s: Silver has an unusually strong cat on f2.
- 8g Rf1n Mg3n Rh3w Cc2e.
- 8s Dd3w ee3w cd4es. It is unusual for a cat to be such a strong attacker in the opening, but the alignment leaves Gold limited options for dealing with the silver cat.
- 9g Dc4ee Ed5e Rc1n. Gold could have used his elephant to neutralize the silver cat and create a threat in f3, but this would have allowed Silver to begin a race that Gold could not have won. After 9g Ed5es ce3s Ee4s 9s Dc4n hb4e Dc5nx hc4n 10g Rf2e Cf3s hf4sx Mg4w, Gold's horse-to-dog lead would have been short-lived; on 10s, the silver camel could have immediately dislodged the b3 horse and thus captured the c3 dog, while threatening further captures in c3. Alternatively, the silver elephant could have first threatened the gold camel in f6. Gold thus opted for a 9g that saved his dogs; the silver cat remains a strong attacker.
- 9s ce3s Rf2s ce2e ed3e. Silver gets an away frame. This frame is not yet solid, but poses a problem for Gold.
- 10g Rg1n Rf1e Re1e Dc3e. Gold declines another tempting move: the gold elephant could have captured the f7 rabbit in f6, where Gold would have then had follow-up threats. However, after 10g Ee5nn rf7sx Ee7e 10s cf2ew Rg3s Cf3x 11g dg5w Mg4n df5nx Mg5w 11s ee3e hf4es ef3n, Gold would scramble to avoid disaster in f3, and Silver would at least get ahead. Gold was thus correct not to go for such an attack on f6.
Before 16g: Silver has a high camel hostage.
- 10s rh8sss rg7s. By unfreezing the h4 dog, this move threatens the f3 cat.
- 11g hf4n Mg4w De4w Ee5s. Gold had to break the frame, and used his camel so that his elephant could remain in the center. Now, however, a silver dog will reach g3, and the gold camel will become the pinned piece; to protect it, the gold elephant must then stay on e4.
- 11s dh4w Rg3e dg4s hb4e. The silver horse steps east, threatening to flip the gold dog toward c6 and also making way for the silver camel to advance. Gold could now capture the silver horse, but Silver would then capture a cat and camel in return; after 12g Dd4n Ee4w hc4sx Ed4w 12s hf5w ee3n Mf4n Cf3x ee4e, the gold camel would be hopelessly forked.
- 12g Cd2s Dd3se Dd4s. Gold aims to break the new f3 frame from behind. Given Silver's next move, perhaps a step should have been spent occupying b2.
- 12s mb6ss Hb3s mb4s. Silver's camel advance renders both gold horses passive.
- 13g Cd1n Rb1e Rf1w. Gold uses a phalanx to block the silver horse from c2, and prepares to push the silver cat to f1. Gold must beware of the silver elephant moving from e3 to d3, perhaps framing a piece in c3.
- 13s hc4s Dd3n hc3e hf5w. Silver continues the attack on c3, and is becoming increasingly strong across the board.
- 14g Dd4w cf2s De2e Rh3n.
- 14s re8ss he5ww.
- 15g Ee4wn hd3n Cd2n. Gold cannot protect everything, and allows his camel to be pushed north.
- 15s ee3n Mf4n ee4e dg3n. The g5 blockade completes a nice high camel hostage.
- 16g hc5w Ed5w Dc4w Ec5s. The gold camel cannot escape f5, and much is at stake in the west. Gold abandons his camel and aims to capture a silver camel or horse in return.
- 16s re6ws Cd3w hd4s.
- 17g Ec4e hd3s Ed4s Cc3n.
- 17s hb5e Cc4s hc5s dg4s. Gold cannot regain full control of c3, and will lose it totally if the gold elephant leaves. The gold horses contribute nothing in this fight, and Gold is overloaded. By using an HH setup, Gold risked such a position.
- 18g Ha3n Db4n Ha4n Cf3w.
- 18s Mf5nx ef4n rb8s rd5s. Gold loses his camel for nothing.
Silver's attack on Gold's camel trap worked perfectly. Gold made a few mistakes, but the biggest one may have been his initial setup. A case can be made that Gold should never use an HH setup if he is simply trying to win, as such a setup is easy for Silver to exploit.