I play many games, but Portal is why I am on moddb. I make puzzles with BeeMod mostly, tho I am branching into Hammer slowly.
epic
Fun game, but limited and simple. The Developer is slow to add new features and fix bugs but there aren't any major bugs that are being ignored. Great price, fun to play and easy to master. I have gotten all the achievements in the game and still play because it's fun.
Great puzzles, great atmosphere, great story.