I'm kinda surprised that i see no mention of kokageno games since they have heavy femdom snuff themes (guy getting vored and disolved, guy gets his guts eaten alive, guy gets dissolved in acidic breastmilk, etc)
The Demon Angel Sakura series has some wonky gameplay but very nice scenes and Domination Quest is a nice little RPG. Both series have official english translations and, if i remember correctly, have options to unlock all scenes
http://kokageno.net/adult/?lang=en