> Does every discussion about a FPS game need to point out it's the same concept as Doom or Quake or whatever?

Well the great differentiator between puzzle games is the idea of the playing mechanism. The great differentiator between FPS is implementation. If I make an FPS, I didn’t really steal from Doom because the idea is pretty obvious. But if I make a sliding game that’s very similar to 2048, you might say I stole the idea. It’s like with patents, subjectively the mechanism of a FPS shouldn’t be patentable to me, but three or 2048 might be.