Draw one card, then play one card. That's all the rules there are to Fluxx... well, in the beginning, anyway. It tends to get a bit more complicated than that. The game of ever-changing rules is endlessly reskinnable, and Looney Labs has a new one for you Trekkies out there. They've released Star Trek: DS9 Fluxx for your gaming pleasure.
From the website:
Explore the farthest reaches of the universe in Star Trek: Deep Space Nine Fluxx! Work alongside Benjamin Sisko, Quark, Jadzia Dax, Worf and all your other favorite space station personnel while you try to gather Gold-Pressed Latinum and study the Wormhole, but watch out for nasty Surprises and Creepers like the Founders and the Jem'Hadar!