Although not really a game per se, this is such a beautifully-done puzzle that I couldn't resist. XJig lets you turn any GIF into an online jigsaw puzzle, and to add a nice twist, the pieces are double-sided, so you have to figure out which side should go on top. The puzzle interface is great; pieces snap together in a satisfying way, and they can be pushed around on the table just like in real life. If your machine can handle it, you can even play on the root window. Try it with adult pics for a real treat. :)

License: free