RPGM - Kilgor & the Succubus World [v0.9.5.1] [Troll ol]

0.9.5.1, Joiplay on Android, all content completed.
Runs on an ancient game engine, has several confusing progression requirements (Linda's bedroom has the Bomb for the wall, you use Tineli's Necklace for the Blue Stone, Alysson is found at the bottom left of Faradrim Desert's camp map and accessed from the southern map), throws one extremely unbalanced boss at you near the end, is extremely backloaded in terms of content and quality, and definitely needs a proofreader/editor.

Get past all that and you have one of the most in-depth level drain games I've ever seen. Either your HP, MP, or levels will get drained pretty much every five seconds.

30+ different succubi to fight, each with different combat styles and progression as they drain you while you watch their max HP slowly increase.
Breast expansion, ass expansion, gradual brainwashing, enemy turning into a succubus, enemy turning into a higher ranked succubus, skill stealing, stat draining, HP/MP drain on almost every attack, soul sucking, tail/boob/ass/blow/hand/pantyjobs, et cetera. Note that all drained levels and stats are returned when winning, which doesn't detract from the experience since regrinding after every fight would be a major headache.
For succubi that change in the middle of combat with breast/ass/whatever changes, which are half of them, they gain new sprites, CGs, and dialogue for the remainder of the fight alongside a non-overwhelming difficulty increase. I consider this mechanic to be one of the game's highlights. A few have multiple transformation stages. In particular, the not-final boss has an entirely different fight if she drained you enough times in a prior one.
Combat is normally on the easy side with the exception of a couple of endgame bossfights, although part of that is fishing for extremely powerful status ailments from your skills and scoping out elemental weaknesses.
The game has generic RPG random encounters that die in one/two hits and act as EXP/item piñatas.
Towns and dungeons are mostly just there, but at least the dungeons usually have some sort of gimmick or puzzle to prevent them from being completely monotonous. The dungeons definitely do not overstay their welcome, being just the right length.
There are two artstyles in the game, with the second one coming much later and generally featuring much more complicated CGs. They're both well-done however.

For improvements:

1. A proofreader/editor is needed to check almost every line in the game, especially earlier ones. The two main issues are incorrect punctuation (in a consistent manner) and incorrect verb tenses. Unlike MTLs however, it's perfectly understandable as to what is being conveyed.
2. Some of the earliest game content needs a touchup to have similar quality to the middle and later parts. For reference, the first bossfight has a static standing image and a footjob CG with a cumshot. A random hard-to-find optional bossfight halfway through the game has four different standing images, a blowjob CG, another footjob CG with 3 variants, and a transformation (technically two).
3. Even with Yanfly's plugins, VX Ace is aged for a game still under development. The game's simple enough from a programming standpoint that changing engines wouldn't be too difficult, but this is low priority.
4. A way to check enemy stats and/or profiles would be nice.

tl;dr, if you can get past the first hour or two and aren't bothered by imperfect English, you get what I'd consider to be one of the best implementations of level drain mechanics-wise.

Harelixia is my favorite of the enemies, being a smartly-dressed potions master with a cool colour palette and a fairly fun fighting style. Also, her boobs grow, though sadly only if you lose, but she does have a proper combat and field sprite for it at least.

An excellent femdom / level drain game. Though if that's not to your liking this game probably isn't for you.
Each succubus is a boss with a number of special moves and other tricks to try and seduce you, fuck you, and level drain you. Many of them will grow their tits or ass from draining you, and become more powerful. And then you get a game over.
The translation is not perfect, and there's some flaws here and there. Some of the bosses, especially in the late game, are very mechanically interesting, while the ones in the early game are less so. However, there's a ton of content, and a gallery where you can refight the bosses, which is the best part of the game.

I'm giving it 5 stars as I really liked it, despite some minor issues.

I love myself some femdom games mixed with succubi/monster girls, and I don't even mind grinding in rpg's as long as the reward matches the work. Unfortunately, a terrible endgame dungeon mixed with a barely-there story does not a good game make.

First and foremost, the story. It's a pretty neat concept to make this an isekai story. Unfortunately, much of your goal of getting home is exposited to you by npcs and your few moments of autonomy are in deciding to auto-kill yourself to bosses or to fight them. There are no known sidequests (not that I checked), so it's a pretty straight line towards the end goal. About 80% the way into your fetch quest story, your main character starts seeing visions from the past. The context basically spoils the final boss around 2 dungeons before the final dungeon (which has around 4-5 bosses apiece, with the final dungeon having around 10+). If these visions had been spread throughout your journey, it could have been a neat build-up towards a heart-wrenching confrontation.

The combat is fine, to a point. The mobs drop massive amounts of gold and exp which would sound fine in theory, but the overall design of purchasable stuff and leveling becomes a slog after a period. The final dungeon does provide a ton of extras like exp potions and stat boosters, but the benefits from those are too low to matter. It doesn't help that the final dungeon has bosses that will wipe the floor with you even when you max your level, making the entire point of grinding pointless.

Speaking of, the art of the succubi is actually pretty good. The problem is that the developer didn't put much effort into ensuring that when certain scenes zoom in on a part of the art, the art didn't just pixelate into a barely discernible mess. Couple that with the fact that the balancing issues around boss battles becomes painfully apparent in the final dungeon to the point where a boss can spam their level drain skill and you can't actively prevent it, which leads to a frustrating experience.

Honestly, I liked the art, the scenes (although, if English is not the dev's first language, I would highly advise in favor of finding an editor), and the neat story concept that emerges far too late to be anything but a desperate last-minute attempt at weaving some form of emotional weight into the story. The problems, unfortunately, bring this game down. Things such as mobs spawning too often, and balancing problems make it an almost unplayable mess from start to finish. Its one saving grace is that, as the dev's first project, it can also start as a foundation for future games that improve upon where this one fell far too short.