Elite Dangerous.
Sure, the game looks nice, and I like the concept, but the lack of a demo made me a bit wary, and then when I bought it, dear god, the controls...
Yeah, no, I got a refund. Steam says I have "0.7 hours played". I think most of it was trying to get the damn thing to work. I'd say it was a waste of money, but as I said, got a refund, so it was just a waste of time I'll never be able to get back to waste on something else.
Though, that's just the most recent one I can clearly remember. I think I got Dead or Alive 4 or something like that for the 360, and got bored after one match. Dead or Alive 2 really held my attention, but whatever the one I got for 360 was, it just couldn't hold a candle to 2.