Fluxx is never the same game twice by Daniel Heck
"Do you remember how Calvin and Hobbes, in the classic comic strip, used to play Calvinball? They'd basically make up the rules as they went, changing them at whim and having a blast in the process. While you can't make up just anything on the fly in Fluxx, this popular card game does give you the ability to change the rules and even the end goal as you go. With its unpredictable nature and great card variety, Fluxx makes an excellent game for parties and large groups."