The GemRB Game Engine is is a port of the original Infinity Engine (the one of Baldur´s Gate, Icewind Dale, Planescape: Torment, etc...) to Linux/Unix, MacOs X and Windows with some enhancements.
Quote:
GemRB V0.6.5 (2011-07-24):
New features:
quickspell support
keymap.ini handling
yet more unhardcoded PST projectiles
area comments, party npc interactions
ios port and enhanced touchscreen support
Improved features:
performance
squirrels and other small game don´t die instantly