SNES:
Chrono Trigger
Super Mario RPG (God, I wish they would port this to GBA/DS)
Sailormoon RPG (only done through emulation, of course)
Donkey Kong Country (1, 2, and 3)
The Legend of Zelda: A Link to the Past
Final Fantasy IV & VI
PC:
Master of Orion (1 & 2)
Master of Magic
Civ (I and II)
Alpha Centauri (and the Alien Crossfire x-pack)
SimCity 2K
An awesome little RPG called Castle of the Winds
Mordor: The Depths of Dejenol (which has nothing to do with Tolkien)
High Seas Trader
Lords of the Realm (I & II)
Lords of Magic
Betrayal at Krondor (this actually took me away from the PC for a bit by inspiring me to read just about the complete works of Fiest)
Original Game Boy/GBC:
Donkey Kong Land (1)
Legend of Zelda: Link's Awakening
GBA (Is this "old" yet?):
Baldur's Gate: Dark Alliance
That's all I can think of right now, though there's probably more.
Edited, Sep 30th 2010 10:15am by ShadorVIII