PC: definitely the Lucasfilm Games classics.
- Monkey Island I & II
- Day of the Tentacle
- Sam & Max
- Indiana Jones
- Grim Fandango
NES:
- Kickle Cubickle
- Faxanadu (maybe it's just me though)
- Snake Rattle'n'Roll
- R.C. Pro Am
SNES:
- Illusion of Time
- Axelay
- Parodius
Currently playing: NSMB (Wii)