Year Zero Engine ALL THE THINGS!!!
Fantasy = Forbidden lands
Si-Fi = Mutant or Corolis
Modern = Tales from the loop
Horror = Alien
For example Mutant Genlab Alpha would (almost) be able to be used straight up for Vampire or other WoD games.
The good thing with the system is that it is pretty easy to add and remove rules to get the right feeling for the setting you want to play in.
Genlab use Feral Points for the animal side of the character, Alien use Stress Dice, Forbidden Lands has magic and magic items., Tales has a mundane/investigation scene mechanic etc.