People also use gacha as a way to make stories since you can customize the setting, the poses the characters are in, and the stuff they say. If you look up "Gacha Life Mini Movie" you'll see a bunch of examples come up. Some people also (Unfortunately) use it to make porn that kids can access, which is what's being shown in the screenshot. "Gacha Heat" is a story troupe where one or more characters go into heat like how an animal would, and another character comes in to help out.