Mutagenic Substance blog. I've gotta tell you this is a Great resource for mutant future or any mutant related campaigns. To play the game as designed you are basically law enforcers keeping the peace against some seriously twisted mutants lurking in the slums of a dark and gritty future. That's ok, but is not what jumps out at me. Where this game really shines is in it's mutant generation rules. You can really go to town and roll up some interesting and quite freakish looking mutants. One thing I'd like to see more of in Mutant Future is a greater variety of mutations. After making several NPC's and mutant beasts I've found the mutations become a bit repetitive. With this book you can really create alot of individuality in your mutants.
The book is long OOP but still around in places. So if you can snag it up for a decent price I highly recommend it.