1996. My Dad worked as a system builder for a reasonably sized company for a few years when we moved to New Zealand, and he'd bring home copies of those freeware/shareware software compilations that they used to include with their PCs. That's what I grew up playing: Doom (Episode 1 only, of course), S.C.A.R.S. (if anyone still remembers that game and knows where to get a copy, PM me), Jetpack, etc.
Then when I moved, the computers at my new school had GliderPro, Lemmings, and Sim City 2000. I used to get to school at 7:30am and play until school started, then when I had finished my work I'd play some more.
Those were the good old days. The graphics sucked, but the gameplay was fantastic and the games themselves seemed endless. I had the best time ever. Now I have Dota, Mass Effect, Civ V, and other great games, but somehow they still don't feel as good as when I was 9 and guiding my lemmings to glorious victory to the sound of a MIDI-fied Turkish March.