>Pretty much any fighting/action/rhythm game
I have never been a particularly dexterous guy, I can't handle memorizing and executing combos or large series of inputs. Best I can do is just get good at a few inputs, so if the game can't be beaten with button mashing/easy combos, then I can't do it.
>4x games
Particularly Civ 5 and Stellaris. I just can't figure these games out. In Stellaris I can get a good start but I inevitably resource debt death spiral until I lose, or I just don't progress fast enough. Civ 5 I just don't get how to do better, I try to go for science whenever I can and always end up behind, never have enough army, unhappy pops, etc. Total shitshow, can't beat the game on prince or whatever the default difficulty is.
>world war games
I don't really like history much and this isn't a mechanics problem for me, I just dislike the subject matter. I don't know why some people get so obsessed over playing games set in the world wars, I find them boring and repetitive. Might just be my distaste for politics. Hearts of Iron 4 comes to mind, could not get into that game at all.
>soulslike games
Medieval fantasy never grabbed me concept-wise and I don't like the combat. Roll/parry/slash isn't fun to me. Got about 20 hours into elden ring before dropping it out of boredom/frustration, haven't tried any other souls game and have no desire to.