I would add to this list:
1.) Captivity by Perveloper - there are rather interesting modding and concept art sections on his Discord...too bad Perv dropped the idea of expanding the game due to his personal stuff and spaghetti code of his own making because the game had a HUGE potential for modding if Perv would embrace the idea.
2.) AQE by Grimhelm - really curious mods (at least 3 versions of HardMode and one Cheat/Dev Mode), pushing the limits of modding for that kind of game by adding new stats and enemy variants that have different behaviour (like the toxic green variant or purple variant that has increased damage during sex scene and can move at faster pace) -
here the f95 thread.
3.) Corruption of Champions by Fenoxo - first game was fully open-source and it allowed the creation of really big mods that expanded and actually finished the game the way Fenoxo and his retard-squad never could (it got to them so hard that they decided to not go open-source ever again with CoC2). Biggest are: Revamp by Kitteh6660 (Unofficial CoC 1.5), CoCAnon Mod (CoC 1.75 - recommended expanded version of Revamp, available
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), CoC Xianxia (a chinese+weebo sword fantasy mod with rather poor quality of writing but good amount of effort for what it's worth).
4.) Violated Heroine - they try to rebuild the entire game in a different engine on Discord, so yeah...
5.) Pretty much all of Illusion studio's games (especially Honey Select 1&2, AA2 and Koikatsu).
6.) No Haven - Loaded Dice Mod is basically how you should play the game to avoid brain damage from Rags acting retarded 99% of the time and you not being able to fix anything about it midgame.
7.) Night Of Revenge - there was some success with adding a new animation from one of our fellow modders on Ulmf! A good place to start learning about messing with Unity for that kind of games.
The more open-sourced the game is, the better mods you'll have. The less over-complicated the game is, the more interesting and easier the mods are as well.
Guilty Hell is neither of the above, so don't even think you'll have anything mod related in both GH1 and GH2.