I can think of a few...
Tigers Unleashed was a novel effort, but it looks horrible and controls worse. I have never seen a game that takes seven steps just to move a unit. It's just tedious through and through. And because of the utmost amount of realism in the calculations, it takes upwards of a minute to calculate each of the turns, even on my beast of a computer.
And then there's Seduce Me. I got gifted it as a joke, but it's pretty bad. It's a casual game and you can tell it is, but pretty much all of your progress
in the game is determined by card games. And the random dealing of the cards regularly
puts you in situations where you lose no matter what. It doesn't matter what kind of game it is, it's not fun to watch a decent amount of progress slip away based on being dealt a bad hand.
And then don't get me started on Death and the Fly. Ugh. It took me 15 minutes and a Youtube video to figure out how to start the first level. I barely noticed the glowing green circle that was the "tutorial" level (which actually just pulled up the help menu I'd already found) among all of the other bright colors on the map. THEN it took me another 2 minutes to realize that it had opened up a real level, another nearly invisible green circle. AND THEN once I got in, the fly moved really, really slow, and it wasn't clear what each of the characters was supposed to do. And then the music. Ugh. That was annoying.
And Carrier Command: Gaea Mission. I tried the demo. I love the gameplay. The graphics are pretty nice too, and it runs well on my computer. The AI is absolutely horrible. I watched a unit go 50-100m off course and run straight into a wall. And apparently it was never fixed.
And I'm not a huge fan of Colour Bind either. I got it for free, but I wouldn't ever recommend it. It's a physics-based puzzle platformer and it seems like the physics work against you nearly 100% of the time.
I also don't hate Really Big Sky, or think it's a bad game, but I found it really dull and I don't get the appeal of it.
And then there are the obvious ones like Daikatana, Revenge of the Sunfish, etc.
something Derek Smart made
UGH. Even for free, Battlecruiser Millennium isn't worth it. The controls are horrid, it's overly complicated, and it's a bit empty.
And only All Aspect Warfare could make shooters complex in a bad way. Trying to learn to control my character well was like trying to fly a...well, a battlecruiser.