Space Empires 5. I had so much love for it. Even got a nice balance mod for it.. but its core coding was so bad it was simply getting too hard to reach the "fun" parts, especailly when we had a powerfull computer and even that coudnt get it to handle fleets of more than 20 ships without -massive- lag.
At least the battles were fun to watch. I loved designing each of my ships with tender loving care, making each of their coponents, weapons and individual strategies fit with the big picture i had for my empire's military doctrine.
Oblivion. Because it hated me and my playstyle. It was all over mages and their flashy, boring and unbalanced magics and never allowed me to get any enjoyment when i didnt want to use it. At high level, even with mods, it just got too long to kill anything it stopped being fun.
Sword of the stars. Just like Space empire 5, it started by being pretty good. I loved it a whole lot initailly. I liked how pretty much everything worked, even with the weird trading/freight system.. even with the (very) poorly designed UI (i only discovered i could do diplomacy a whole YEAR after i had it, never realized there was a button for it!)
..Then the combat system started to really get on my nerves, on how my fleets were so long and boring to organise, how the battle controls were confusing and obtuse, how the number of ships in battle was severely limited (so it was pretty much useless to get massive fleets, yes im aware of CnC ships), how combat was slow, boring and that my ships just kept ramming/shooting eachother all the time like morons.
Basically, the one thing that should have been fun in this game; the combat, wasnt fun at all. At the end i never, ever bothered fighting my battles manually. No matter the odds or the numbers or whatever i just let the AI get it over with.
Resident evil 4. I simply didnt enjoy it. I dont see the fun in it. I dont like the camera angle they force us to play with. I hate escorting a useless little girl around in waht should count as a warzone. I hate instakill QTEs.