CrystalBall is the best damn D&D RPG tool on the Mac. The fact that it's also one of the only D&D RPG tools for the Mac is beside the point. Available as a shareware trial download, the program is comprised of a dozen or so different utilities for your game that can be used in or out of the game.
Warcraft III is a real-time strategy game in which players take on the role of one of four factions in a bid to save -- or damn -- reality from a demonic invasion. The game's divided into three modes: story (single player), customized game (single player) and multi-player.
In story mode there are four thematically-linked campaigns, one for each of the game's races: human, undead, orc, and elf. Each advances the overall story, which involves the demonic forces of the Burning Legions' attempt to invade the real world. Only one individual -- the mystical prophet -- is aware of the Legion's intentions, and he does his best to warn the good people of the coming threat. However, the Prophet's message is one that few embrace -- he advocates fleeing before the heralds of the demons: undead under the command of the lich Ner'zhul. That's more than Prince Arthas can take -- he steadfastly refuses to abandon his homeland, and instead journeys north to fight the undead menace. There he must decide between vengeance and salvation, and the wrong choice could damn the world.
The Sims is a strangely compelling simulation game that let's players micromanage someone else's life.