Spelunky is a charming, super-addictive platformer which has earned a reputation as a tough, but rewarding old-school gaming experience. It has been available on the PC, free of charge, for almost four years. Recently it made the jump to the XBLA, where it has received updated graphics, new secrets, co-op play, and more. All of this comes at a cost, of course. Is Spelunky a treasure worth the price of admission? Find out in our Co-Op Review.