Yeah I am a huge fan of Portal. The amount of time put into the writing and voice acting alone would make the game for me, even if it wasn't incredibly fun. I frequently find myself trying to beat the level just to see what will be said next. That says a lot about writing in video games to me :) If you haven't played Portal, shame on you. Repent and go treat yourself to one of the better games of our generation.
This is some fan art that I whipped up today.