I forgot to add, it needs to be free. I did download GURPS Lite a while ago. I can't remember exactly why I didn't like it, but one problem I see is that it has a specific list of weapons. You can't just make your own with whatever set of attributes you want. And there's going to be statistically better and worse ones, so you have to choose between the weapon you think is cool and the one that deals more damage. In contrast, Mutants & Masterminds has weapons with a point buy system same as the characters. Though it's extremely bad at explaining that. It just has a list of Devices and their costs, and you have to notice that the example characters have weapons that aren't in the list, and that they cost the same as if you just build them into a player but with Equipment Points instead of Power Points.

Also, Lite at least doesn't seem to have any way to build characters with interesting powers. I don't really care if it's superhero-themed in particular, but I just think M&M's system of design your own spells is better than D&D or Pathfinder where you just have to pick one out of a list or or make your own and eyeball it.