Non adult? FO4. I just... cant. So many things I disliked that mods fix. I mod the shit out of that game and have played it many times. Same with CP2077. I saw videos of it unmodded, didnt like shit, and the first time I bought it and installed it, I put mods in before playing it. That's become a bit of the usual for me though.
EDIT: Oh, forgot minecraft. I refuse to play vanilla minecraft. I just... cant. Ive played modded so long, thats the only way for me.
Porn games? Well... I almost always install a walkthrough mod if it is avail. Sometimes gallery mods, but I dont really use galleries often. If I just want to see porn pictures, I can go browse the folder. Or google "titties". But... there are a few games ive played a few times and I edit the shit out of them.
DoL(P). Same with CP2077. First time I saw gameplay previews, I saw shit I didnt like. Found out about DoLP (P=Plus), and decided to try it since it fixed a lot of stuff I didnt like. But... there was still stuff that annoyed the fuck out of me. Mostly the time things take. So, I learned how to read and edit precompiled-to-html twine/sugarcube. Then I hand edit the html file to change things. 1 hour tasks? Nope, 10 minutes. 20m? Nope, 5m. 10m? Nope, 1m. Also, lots of things SHOULD give you stat boosts that don't, so I edited those in. Sometimes I would edit it to make the game harder, mostly just because my editing the times down would make it easier. But I was editing them to reduce the boring "oh, its getting late, so lets travel home slowly... shower, go to sleep, dress, leave, do daily shit and then finally return to what I was trying to get done" grind. I also modified it so when the MC had the succubus TF, instead of just lowering stress when creampied, she also lowered her tiredness (so energy, which is what most lore ive read says is what a succubus gets from semen). Not enough to make a massive diff, but usually enough to recover what was spent in the gangbangs she usually got caught in, and a slight bit more.
TheFixer. I like the games framework more than the game itself. Not a fan of the whole character-sprite thing in adult games, but they did it halfway decent. The dev also made the framework so that a lot of stuff could be added in to improve the game later. I disliked a lot of the grind just like in DoLP, so from the start I would make small changes to the code directly. Usually reducing stamina usage or time passage. In some scenes, such as in the brothel, I would remove the "he wont fuck you because you have cum on you" because... those places and the fees charged didnt seem liek the high class place that would care. So mostly little shit. But after playing it a few times, I couldnt stand to play it without making my edits.