Mutant is a Swedish post-apocalypse RPG originally published in the early 1980s as a BRP game. It has thrived as a BRP game for many years, but recently a new version was released with a completely different set of rules. It's been very well received here in Sweden, and now it has been released in English. I warmly recommend it! There is an in-depth review at http://www.rpg.net/reviews/archive/16/16316.phtml