AAAAHHH, STEAM.
Portal has been the only reason I haven't been bored, really. XD
I was quite impressed by the coding and technical whatnot; especially how they averted the "Portal Cut." (Portal Cut is what happens when a portal closes before you get through and you get sliced.)
Lol, TF2 seems really fun as well. Amnesia gave me frights for a whole week, thanks to those things with their flappy jaws and those other things with those....UGGGUGUGUGUGUHHHH. This is why I don't have Amnesia, I simply watched playthroughs of it. XD