I'd have to say EVERY Star Trek game ever released, except Star Trek: Encounters for the PS2. The controls can be a bit...erratic...if you get caught up in events, but but overall it had good graphics, usable controls and entertaining gameplay. Scratch that...Armadas I and II weren't too bad either, but pretty much all the other Star Trek games have been a vomitous insult to Roddenberry's creation.
Most Star Wars games. The adventure games are usually pretty ok, but most of the RTS style ones are just revolting.
MoO3. I can't even begin to go into how this game doesn't compare to its predecessors. The graphics are 3d, but not much more complex in color or texture than the previous games, and much less interesting to look at. Most of the UI was an alright idea, but poorly executed in both function and appearance. It was just mind-numbing to look at, and was almost counter-intuitive in layout. The AI was atrocious on every level. Creating an AI that gives an impression of how subordinates in your administration would carry out your orders in their own way is a good idea...but creating one that fights me every step of the way because I do things unconventionally just pisses me off. I have issues with games that restrict one's chances to "think outside the box" but I understand the limitations of technology, but to actively work against my efforts, and punish me for finding alternative paths? I nearly snapped the disc in two and burned it...but I didn't. As for the mods...if they turn off the "hidden" AIs in the government process, I'd try em, otherwise, this one's a dust-collector for me.
Genesis Rising. Tiny, tiny ship cap. Disastrously simple and clunky controls. Candy-coated, and frankly lazy, b-movie graphics and art style. The armor that the Earth soldiers wear is like that garbage from games like Unreal and Gears Of War. Gigantic, "I can't wipe my ass, put my arms down, or see anything to my left or right because of my armor" shoulder pads and crap. I hate that...HATE it! It's beyond stupid. What I hate most of all...is how the story concept was really quite exciting. But between limited scope, bad graphics, horrid dialogue, and less than adequate gameplay, this game wouldn't have been worth it even as freeware.
Metal Fatigue. This is just like Genesis Rising, only better...but not by much. The graphics are only one step down from Supreme Commander, but the real problem is how buggy the game is...and it never got patched, to my knowledge. The 3-way faction split is a little generic, but I've never cared about that sort of thing. Stat and capability-wise, you can only specialize in so many directions at a time, and only to a certain degree...that's just the way it is. Visually, the same is mostly true...you can only take their appearance so far from the basic before it just becomes ridiculous. Ideologically and "culturally" you can split factions as far as you want, but I'm sure no one here cares about that. My only real beef with Metal Fatigue is that the UI wasn't as smooth and broad in function as I'd have liked, and the utterly bug-frakked nature of the game.
Arcanum: Of Steamworks & Magick Obscura. This game disappointed me, but I still do enjoy playing it. This game was buggy, but really what disappoints me is how it's alright in many ways...but never quite made it to the glory it could've had if it'd just been done a LITTLE better than it was.
Master of Magic. This game didn't disappoint me at all, loved it. What disappoints me is that I found it as fun and engaging as MoO I, and yet MoM never got a sequel...not one. I want a MoM sequel, especially in light of all these other ground-based RTS games and other Civ-style games. Oh well I guess.
Sorry for the longwindedness everyone. Didn't wanna just list em though...was afraid people might inappropriately add my list to their "votes that a particular game sucks" Don't want them doing that in any case...except MoO3.