Sorry Wasteland, as much as I love Fallout 1/2, and Wasteland being their direct ancestor, I voted Pools of Radiance - not only it was AD&D game, but was also precursor to later Black Isle/BioWare games that went on to define isometric CRPGs.
Other great games from that year I remember are Laser Squad, direct ancestor of X-COM (UFO Enemy Unknown), Hostages (which was later compared to Rainbow Six), quite a few adventure games and last, but not least (since it's the game I played a lot) Carrier Command (mix of real time strategy and sim)