Starcraft. I can't really explain why, but I don't get why it's been so popular for so long.
Supreme Commander 2 I haven't played but the maps are smaller, the new "character driven" story isn't nearly as good as the original's infinite war, the units look like plastic toys, and the experimentals are actually smaller than the ACUs. Forged alliance was more epic in pretty much every way and apparently requires less micromanagement than the "streamlined" SC2, but people seem to like it for some reason.
Nintendogs. I love animals and I still don't get why anyone would want to play nintendogs.
Fallout 3 was good for one playthrough and then I got bored with it. Maybe one day i'll try the "Real" fallout games.