Recently I've played Exanima for a few hours because the premise of a ohysics-based combat system sounded good. The execution is terrible, the main gameplay is boring BUT the combat can be fun at times when it doesn't feel broken. It feels like the game had a lot of potential but was put together by people too incompetent to fully realise what they were making. Physics-based sword fighting is a fantastic idea. Destroying your physics based combat with terrible scripted attacks makes zero sense.
What games have you played that were bordering on being something you like but for some reason failed?