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Speaking of Pathspace.
This game takes into account not only good game design, but the mystic forces of the universe as well. Be warned, this game is not for people without spiritual courage and a bright and honest future, as it WILL bring enlightenment to the player, regardless of whether the player wants it or not. I did not, and I still regret the changes the game produced in me to an extent, but once you've played it, you can't go back, you have been touched by something.
Pros: Brings the reality of the universe thrilling into your brain like a flood, in a small package, at a small price. Also it's fun.
Cons: Enlightenment is not all it's cracked up to be, in some ways I wish I could go back to my simpler self, and not be as all-embracing.