Darksiders I picked up and put down, but I can’t say I was disappointed at all, as I had no expectations. Similar story with Deus Ex Human Revolution, Prototype, and Metro 2033. I just didn’t get into them. I either got them as part of a bundle or tried them out for free, so no harm done.
I picked up Bastion as part of a bundle, however, and still felt disappointment. I really wanted to like the game and had some expectations. I felt the controls were unresponsive, didn’t care about the narration gimmick, and set it aside.
The biggest disappointments are when the bloody thing just doesn’t run and I really want to play. I bought a new copy of Civ IV when I got a new PC recently and it won’t go. Worse, maybe, is when I like the little bit I can play, only to have the fun abruptly end due to bugs, like my experience with Knights of the Old Republic.
Probably the biggest disappointments in terms of genre are RPGs. I like some RPGs a lot. Fallout 3, Borderlands, roguelikes, Skyrim, Shadowrun, and so on, I like them and consider them all to be some type of RPG. I’ve tried some highly-regarded games, like Dragon Age Origins, Baldur’s Gate II, Final Fantasy, and Planescape: Torment and actively disliked them. Maybe not right from the start, but not all that far in. I think the connection might be abstract or goofy combat (although that wasn’t really the problem with DA:O, I thought the combat was good if frustrating) and too much flavor text. I liked Torchlight quite a bit but can remember getting annoyed as paragraphs of flavor text scrolled slowly by while some actor intoned each word. I think that once one aspect of a game starts annoying me, other annoyances, inconsistencies, and absurdities become more noticeable. I considered, say, Mass Effect 1 and Fable II to be mediocre games, yet enjoyed them enough to finish them. Objectively, Baldur’s Gate 2 may very well be a better game than Fable II, yet with the “better” of the two I couldn’t be bothered to continue past the intro.