GURPS is the Generic Universal Role Playing System from Steve Jackson Games. Gurps 4E is skill-based RPG focusing on flexibility. You can easily play anything like stone age man, ogre mage, US navy soldier or Zenbuddhist psychokinetic killer robot from future, which likes cats. Crossovers are easily ...
I'm currently reading GURPS4 to prepare myself for DMing. When I read about firearms I thought pistols to be vastly inferior to rifles to the point that if one carried enough armor to possibly survive ...
So there are a lot of great franchises which don't have tabletop RPG's for them and I've seen that GURPS can handle, or give a valiant attempt at least basically anything, and I've seen for example ...