Portal: Prelude is a free fan-made mod of Valve’s Portal. You need to have Portal already installed on your machine to try it, but it’s free.
I’ve got some issues with the game. Mainly, that while where the original Portal was about figuring out how to get through a situation, in this game, you’ll generally know how to navigate a given level, but actually doing it is the hard part. Whereas the original emphasized puzzle-solving, this game emphasizes twitch skills and accuracy. That said, I don’t like it so much, but perhaps you’re more skilled than I am and will make it past the third test chamber.
