A friend of mine convinced me to buy Mutant Football League to play with him. Pretty cheap for a very fun game - it's an American football game. But you have 7 players on a side at any given moment in time. You can also beat the shit out of the players after each play - and you can actually kill players on the other side. If you kill enough players, you can win the game by making the other team forfeit. You can use things called "Dirty Tricks" to do things like bribe the referee, take steroids, use shotguns, use bombs, and shit like that.
All in all, it makes for one of the most fun sports games I've ever played. Definitely the best iteration of American football I've ever seen. The commentary is hilarious too.