The Carnivores series (minus Cityscape, which is fun, but a different sort of game) has a very unique atmosphere that hasn't been replicated anywhere else. The simulation aspects immerse you in the gameplay, but they aren't excessive. The idea of hunting something that you have to kill before it kills you is exhilarating still, even though the game, on a technical level, is quite primitive 20+ years after it was released. For me, this is the type of game that excels in its simple idea, atmosphere, and presentation.