Worst Unreal Tournament
ever. Completely butchered the feel of the game, upset the weapon balance, and included a paltry number of maps and a bunch of useless gametypes. Unreal Tournament 2004 fixed all the wrongs done in UT2k3, but unfortunately wasn't able to woo back all the players alienated by UT2k3.
Basically, UT2k3 showed off Unreal Engine 2's new graphics, while UT2k4 used those graphics to illustrate a game worthy of the Unreal Tournament series.