- I am a bit hesitant in including real porn gifs/mp4 mainly due to copyright reasons. I know that a lot of people do it without consideration, but if I can avoid it, I would. What I could do is to add "hooks" in the "sex engine", so that if you have a gif/video associated with a particular action it will be displayed. This would require someone to create a mod (mainly create an image pack of some sort).
So the rules for copyright in your country may be different but these are the simplified rules where I'm from:
The less you persecute copyrighted material the weaker your claim becomes, this means that while you technically still own it, if you have let 50 people to use your material in a certain way without you demanding anything you simply cannot say to nr 51 that they are not allowed to do the same and you need something from them or you will take them to court. Not to mention the hassle it would be to go after some frankly rando making a HTML game on Patreon, porn companies will likely not care as they know their material is already spread far and wide for free anyways, after all, they even do it themselves.
There have also been several cases where porn have been outright denied protection of copyright in the United States due to being "obscene" and while a few have been persecuted these were full movies, not just clips.
I've seen other people worry about copyright but I've simply never heard of anything ever happening other than some artist likely making empty threats that made the creator panic.
Lawsuits are expensive and takes years if you don't want to settle out of court and some dude taking donations for a piece of work is pretty hard to sue, even if he got your IP because remember, you don't have consumer protections on stuff like Patreon because it's a donation website.
Oh and use webm or mp4, gifs have a massive file size comparably.
cheers.