You inspired me to try asking around, and on ULMF a kindly fellow pointed me to
Twilight Scramble. I am playing through it right now, really like it! It's an RPG maker game, but the animations are all ingame, the gallery is greatly implemented, the game is complete.
Mostly restraint fetish, and an overwhelming majority of enemies and all bosses practice mana drain.
It's great even if you only look at the gallery, but the dev took great care to make elaborate dialogues and scenes, so we kind of lose its full potential without an english translation. I'm making a lot of kanji practice, and there's a already a thread requestining it here on F95.
If you go on ULMF, I've made a very through thread. Sorry for the lack of links, as I said I'm still getting my wings.
This game reminded me of another game,
Miifa chan's RPG. Free, in development, RPG maker, energy-drain focused. Loli.
Again, can't link, but the creator is an habitual poster of the marixyokukyuushuu /魔力吸収 tag on pixiv, and you can easily find it by browsing this great but infrequently used tag — for me it's the 10th post or so, look for the blonde girl wearing blue.
It's similar in theme to Twilight Scramble, not as good due to the lack of content. If you like both and are curious, browse Miifa's tag and you can find a comic by the author of Twilight Scramble where he draws Miifa getting reastrained by one of his game's bosses...
Lili's drain dungeon is indeed good (already knew that one). Melody blood is a great discovery although I already saw some art on Pixiv. Shame the second one is not that full (also it lacks a gallery or a method to trigger all scenes).
Melody Blood is wasted potential: the game. What is there is still amazing.
Not really my style Nightmare Sphere, maybe because it's a little old and I found the drain animations not that appealing (although I did not found the two enemies you mentioned yet).
Eh, if it's not yet working for you don't bother. It's a great game, not a great energy drain game.
Thanks for that! I'll ping you if I find more
I'm absolutely counting on that.