imagine if you had the patent for ball games - lol
It's insane how many computer-game related patents already exist... Pretty much any game is guaranteed to violate *someone*'s patent.
Obvious things like health bars over a characters head? Patented. Using a mini-map in the corner of a screen? Patented. allowing for seperate user profiles? Patented.
(I don't remember the specifics, but read an article on the matter some time ago linking to those examples)
Many of the large companies have a ton of 'stupid' patents just for defensive purposes -- even if they violate someone's patent, they are bound to violate one or more of yours as well, so you're in a bit of a cold-war stalemate. It's the small independent developers without any patents that stand to lose the most in these circumstances.