1) Chrono Trigger (SNES)
2) Deus Ex: Human Revolution (PC)
3) Mass Effect 2 (PC)
4) Sleeping Dogs (PC)
5) Final Fantasy VI (SNES)
6) Demon's Crest (SNES)
7) Zelda: Ocarina of Time (N64) - I'm not a Zelda fan but this left the biggest impression.
8) Dishonored (PC)
9) Street Fighter 2/Alpha/3/4 (any) - Clearly the greatest fighting series of all time.
10) Dota 2 (suck it LoL nerds)
Special mentions: Street Fighter 3 on Dreamcast, Bastion on PC (good soundtrack, cute story, decent gameplay, memorable experience), Tales of Phantasia on SNES (beastly graphics, good sound, good gameplay), Paper Mario on N64, Sonic Adventure on Dreamcast (garbage game but nostalgia prevails, great graphics for its time, and the Sonic campaign was fun).