There are 3 aspects to fapping. The physical, visual, and mental.
Physical is not too complicated I guess. It's your fapping skills. Speed, frequency, grip strength, reverse grip/standard grip/ambidextrous swap. Maybe fleshlight and shit like that if you have it (never tried).
Visual stimulation. 2d? 3d? real porn? Good angles? Graphics quality? Frame rate? short, medium, long animation? Models?
Mental stimulation. Arguably the most important aspect, at least in my mind. Fetish? Backstory? Circumstances? Leap up? Motivations? Ramifications? Implications? Quality of the script?
There is an interplay with all 3 of these aspects for a good fap session. A weakness in one area can be compensated by the other 2. I guess the physical aspect is entirely up to you, there is no need to really think about it.
For a porn game, the mental and visual stimulation is pretty much entirely in the hands of the dev. If the fetish lines up with your preferences and the script is good enough, you can slowly build up your arousal as you play. The issue is that most devs fail at actually delivering the release point with a fappable sex scene. It's just too short most of the time. Minimum dialogues. Shitty 3 second loops.
I don't ever play or watch the same thing twice, so I've already run through most of the games that would be fappable to me. I still do have a huge list of unfinished Miel games that can reliably get me to cum in 1-2 scenes, but for the most part, I'm just playing these porn games for the plot (and some edging).
If I really want to fap, I turn to hentai, JAVs, sometimes 3D comics/SFM stuff, and very occasionally western porn videos. The SFM stuff is mostly for edging as well, but the longer animations can be pretty good visual stimulation, and my imagination can act as a powerful mental stimulation. The characters being parodied have their backstories already and you can head canon your own fucked up narrative to it while watching. JAVs have great visuals and sound effects (I like Japanese squealing, sue me), and they actually have plots that I can figure out even without speaking the language. I can also add my own head canon sometimes. Hentai doujins are the most balanced and reliable fap material for me. The fetish, concise narrative, and the art generally leads to a smooth fapping expeirence. Western porn is decent occasionally, but meh. Too much bullshit to sift through. And the fact that I can understand the plot and their dialogue delivery means that I can't head canon anything or give a pass to poor acting.
Why did I share all this? I don't know. But getting back to the question... I don't replay stuff, but the huge list of copypasta Miel games generally line up with my preferred themes and delivers a barrage of that content in a super nukige style. No real need to slowly build up my arousal and each scene is fappable if you are into the typical hentai dialogue that goes with these themes.