I've had the card game Fluxx for several years now. I really enjoy playing it. I've recently started playing again with some friends. We've been playing the Zombie version mostly. The game is designed to mix versions and create new cards as you wish.
They don't riffle shuffle very well but it's a lot of fun having these new cards in the deck so I employ the Corgi shuffle instead. So that we don't have to straighten the pile back out we play with a messy draw pile, which is more fun anyway.