Psychonauts actually ended up selling quite well, if you include PAL and downloadables. Don't have ready stats though.
Also:
XBOX:- Stranger's Wrath
- Munch's Oddysee
- Azurik: Rise of Perathia
- Beyond Good & Evil
- Bloodwake (got for free, never played more than two levels)
- Prince of Persia: Sands of Time (Didn't get past the first big boss fight)
- Voodoo Vince
PC:- Sam & Max seasons 1 & 2
- Grim Fandango
- Sam & Max Hit The Road
- Day of the Tentacle
- Afterlife
- Full Throttle
- Curse of Enchantia
- Evil Twin (never got past the first level or two)
- Abe's Oddysee
- Abe's Exoddus
- Tomb Raiders 1, 2 & 3 (only finished #1)
- Black & White
- Worms 2
- 7th Guest
- 11th Hour
- Beyond Good & Evil (controls were shite on PC, got the Xbox version and finished it)
- Discworld
- Starship Titanic
- Titanic: Adventure Out of Time
- Heart of Darkness
- Creatures 2
- The X-Files
STEAM:- World of Goo
- Half Life 1 (probably not going to bother finishing)
- Orange Box (only really played Portal)
- Peggle
- Audiosurf