re: I just bought Portal & Portal 2.

First one was great but short. Was originally a tech demo that got turned into a full game.

2 is just beyond fantastic. Writing was taken up a few notches, considerable longer, and it looks surprisingly good for a game on this old of an engine. Fun co-op levels. I'm assuming you're on console. Not sure if it was made available to them, but there is a level creator for the PC. A lot of user created levels to go through.