Space mutants, depending on how they are handled, could turn out really cool.
I'm thinking something along the lines of Halo's Flood. On the surface, they are just that: Zombies in space. But if you delve deeper and learn more about them (or just play Halo 2
) you will learn so much more. Not very generic, lots of cool backstory, the possibility for intelligence, and cool looking designs!
Space mutants can
work. They just need to step away from the whole "zombie in space" thing and bring it in a new direction.