I missed a day so here's the next two:
21. Legend of Zelda: Link's Awakening (GB, also on GB Color & DS as DX)
This is the only Zelda game on my list. I'm still playing through OoT on VC, never completed A Link to the Past (which I really enjoyed) and Twilight Princess just missed out. However, there's something to be said about the first time you play a Zelda game and this was my first. Maybe it was because I played it as a kid, or maybe it was because it was the first Zelda game I'd played, but this fuelled my imagination in ways most modern games don't even come close to realising. The fact that they managed to cram so much brilliant content into a game boy game was an astounding feat on its own. The charming 2D sprites coupled with the superb design of items, carefully crafted dungeons and clever game progression made this one of the greatest game's ever made. I pretty much played this and nothing else for a 1.5 years; it's just a joy to play.
20. Portal (PC, also on PS3 & 360)
This was pure genius. Only a few hours long with a few bonus maps, but everything was sheer brilliance. The innovative portal gun, some inventive, mind bending physics puzzles and a wonderfully funny script. I played this on my own and went through the whole thing in a single sitting. A few weeks later I spent a few hours of a gaming session with some mates going through the campaign and simply laughing at their reactions. Pure gaming genius.
