I was thinking today, about how games (In this case FPS) could have a small thing implemented to make it a bit harder for the players. Then I thought that what if you're playing a FPS and you're attacking an enemy. This enemy could act like he's been defeated when he actually hasn't. So he'll drop and play dead and when you move on he can get up and get an easy shot on you. This could be a feature added onto harder difficulties that would make the game itself harder. What ideas have you had to enhance gameplay a bit more?