What are some things that just get under your skin about games?
For me, it's games that do not allow controller rebinding. I have neuropathy and my fingers don't all work. If I can't rebind buttons so that I have necessary moves (for example: parry) be on buttons I can reliably press the entire game becomes unplayable.
And on console, where I can't refund a game after I downloaded it (fuck you Sony) then it really screws me over wasting what limited funds I have on games I just can't play.
No save option during stealth sequences or generally in stealth-heavy games. Allow me the option to either improvise and enjoy messing up or plan and execute and test every section of a stealth route carefully without having to replay the mission a thousand times, especially when the slightest hiccup will have the whole mission going awry. If that leads to some people save-scumming their way through the entire mission, so be it. Let them play their way.