I, like many others, am a big fan of the First-Person Puzzle game, Portal. If you haven't played it, do yourself a favor and pick up THE ORANGE BOX, which features Portal along with Half Life 2 and its expansion pack, and Team Fortress 2. I picked up mine for 20 bucks brand new. A steal.
Anyway, here is a free 2D flash version of Portal. Great for any fan or newbie alike.
It will help you learn the basic concepts behind the full-on version of the game.
Also, some dude with a lot of time on his hands made an ASCII version of Portal.
