HTZAAR is a Haskell implementation of TZAAR, a great little two-player abstract strategy game designed by Kris Burm. TZAAR won Games Magazine's Game-of-the-Year in 2008. TZAAR has some interesting game dynamics. At each turn a player must decide whether to attack or strengthen his own pieces. The unbalanced number of tzaars, tzarras, and totts pieces leads to several phase transitions in the game. At first tzaars are targeted, but once they're fortified, tzarras become the targets, then totts. It also has a rather distinct transition from mid to end game. Midway through, most effort is on positioning power pieces for attack. But as more pieces come off the board, movement is restricted to the point where groups become isolated from others, which can work for or against you. Anyway, I thought the game would be a fun AI problem. HTZAAR comes with a very simple AI opponent (lame), but I did my best to structure the interface to make it easy to create new AI strategies. I hope a few people try to build and contribute AI strategies to HTZAAR. And if there's anyway I can improve the AI interface, let me know. HTZAAR can also pit AI against AI. The following is a game between two instances of the "lame" AI. For an idea of the complexity of TZAAR, the number in parentheses indicates the number of possible moves at each turn. TZAAR has a large number of choices at each turn because each turn consists of two different moves (n^2). Typical games are between 15 to 25 turns. $ htzaar -s 22 lame lame 1. white (lame) : D7 -> E7 (42) 2. black (lame) : F6 -> F5 G1 -> F2 (6355) 3. white (lame) : D6 -> E6 A5 -> A4 (5867) 4. black (lame) : F3 -> E4 H2 -> G2 (5227) 5. white (lame) : I2 -> I1 C5 -> C6 (4992) 6. black (lame) : F5 -> G4 H1 -> H3 (4345) 7. white (lame) : H5 -> G6 C6 -> C7 (4176) 8. black (lame) : F7 -> E7 D4 -> C3 (4265) 9. white (lame) : G6 -> E5 H4 -> G5 (3464) 10. black (lame) : H6 -> I5 F2 -> E2 (2870) 11. white (lame) : E5 -> G4 D2 -> D1 (2303) 12. black (lame) : B2 -> C2 G7 -> I5 (2742) 13. white (lame) : G5 -> I5 E6 -> I3 (1965) 14. black (lame) : E7 -> B5 G3 -> E3 (2055) 15. white (lame) : E1 -> F1 I4 -> I3 (1303) 16. black (lame) : E2 -> D1 C4 -> D5 (1656) 17. white (lame) : I5 -> F8 C7 -> I3 (913) 18. black (lame) : B5 -> A4 E4 -> B4 (1480) 19. white (lame) : D3 -> C2 B1 -> C2 (608) 20. black (lame) : B4 -> B6 C3 -> C2 (526) 21. white (lame) : D8 -> E8 F1 -> F4 (185) 22. black (lame) : H3 -> G4 B3 -> B6 (314) 23. white (lame) : C1 -> A1 F4 -> G4 (47) 24. black (lame) : B6 -> E8 E8 -> F8 (125) black (lame) Wins! Screenshots and links: http://tomahawkins.org Known bugs: Occasionally HTZAAR throws a Prelude.head: empty list. I'm still trying to track this down.