I think that x com enforcer rates as one of my worst games played
Yea, that one was pretty dire. Poor controls, horrible camera (that some modders apparently managed to do something about) and a really annoying character. had it not been for these issues, it would have been playable (though not good).
In the "AAA" space I would say either Rogue Warrior
And to confuse things, Rebellion also made a game called Rogue Trooper, which is pretty great. So do check that one out.
Anyway, some of the worst games I've ever played: Limbo of the Lost
: Not only did this game steal its graphics from other sources (which is what it is known for), but the puzzles are horrendous and the main character's movement speed just makes it unplayable. Global Domination
: The back of the box told you about the strategic options that you would have when playing the game, and that was basically it. So naturally I expected it to be a strategy game. It was not. Global Domination is a very poor arcadey game about spinning a globe and clicking on missiles. Imagine Missile Command but add the need to strike back, and the very real possibility of the missiles coming from, and striking, some place that you can't see. Deo Gratia
: Unskippable long intro at the start, gameplay that is not explained anywhere (not even in the manual!) a confusing mess of an interface... There might be a good game in there somewhere, but if so you need the patience of a god to actually find it.