These people are simply implying that concepts, directly adapted from another specific video game, shouldn't be made. For example, someone modelling a weapon/item/map from Halo. This is going to anger people because it's simply a replicant of something that has already been created. To be even more specific, it's an specific something that ORIGINATED from another game.
The concept of teams facing teams has been around for ages. The fact that rky even used "light" and "fire" as if they related to the issue, was absolutely outrageous. Light and fire are basic everyday concepts. To use them in a game doesn't imply that they're being stolen from any other game specifically.
Everything is partially based off of some other concept, that's a fact that you can't avoid. But, when people copy something directly, then they simply show the lack of creativity.
