Heroes Of Might And Magic: Dark Messiah for the simple reason that it's the only game I ever bought (or downloaded, for that matter) that I could never get to work. I spent two full days on it, trying to figure out why it kept crashing. I only played the tutorial, and after that it was crash crash crash. Later on it even crashed in the title screen. I returned it and got Settlers - Rise Of An Empire instead. It was just 5 bucks, but I still felt ripped off.