Infinitely respawning bad guys.

I basically stopped playing FPS that do this after COD3 when I watched 100s of germans come out of a small farmhouse in the middle of a field as I apparently never crossed the 'stop spawning' line over the course of 45 minutes. It reminded me of the tardis, only it was a little bigger on the outside.

All shooters tend to do this, and some do it better than others, but I WANT to clear out an area and move on, and a 'line' i need to cross to stop it happening is the most artificial, unimaginative, creatively backrupt solution.