My worst purchase was skyrim for ps3. It must be much better on pc because it was ridiculously lame on ps3. I played for about 4hours and got nowhere. The action buttons to fight are pathetically bumpy and the game is nothing but a bunch of talking. I wouldn't mind if the story was good.
It was about as good as when I tried to play morrowwind back in 1999.
It was not for this year, but my worst video game purchase by far was Dragon Ball Ultimate Tenkaichi.
I'm a huge DBZ fan and the thought of a game that was introducing a create a fighter in the world of Dragonball sounded like a dream come true.
That and the fact that it had the tenkaichi name (which is my favorite Dragon ball gaming series) made this a day 1 purchase for me......sadly it fell completely short on all my expectations.