Ratskinner
Adventurer
Is it possible to have no creative restraints with restrained mechanics? I'm not entirely convinced that's the case. I think some universal point-oriented systems come pretty close to covering just about anything, but I'd also say that none of the ones I'm familiar with (GURPS, Hero, M&M) have completely restrained mechanics that avoid the necessity of GM intervention.
It is, but you have to step the mechanics back away from simulating a "reality" and into mode which many folks around here would call "metagame" (I think, I'm still not clear on exactly how people are using that word pejoratively and incorrectly.) IME, this works quite well, and can solve some of the persistent problems that supers games run into. (Speedsters & resolution, pricing, etc.)