There aren't that many good RPGM corruption games. Celesphonia is certainly good (but not excellent), which makes it important.
The writing
The story is perfectly adequate. It strings together all the usual tropes: magical school girl fights horny monsters in horny locations in a mukokuseki city. There are no subversions or unexpected twists, but some subplots are kinda underdeveloped.
The gameplay
Unfortunately, the lewd aspect of the mechanics is mostly divorced from the combat mechanics with a few exceptions. The number of crafting choices is too big for a mostly straightforward RPGM game (a common problem), but the combat mechanics are actually not that bad, it's not pure filler, although it's only the bosses and the secret bosses that present any challenge on normal difficulty in the early game.
The art
The art is crisp and has no obvious deficiencies other than lacking animated scenes. The game is thankfully uncensored.
The lewdness
Celesphonia is very inventive with its lewd aspects of enemy dungeons. There's more to the game than just "the MC progressively becomes a bigger slut" or "the MC gets raped by every single monster", as the MC has to deal with cursed slutty equipment, hypnotic influence and literal pools of semen guarded by tentacles. The only problem is how easy it is to avoid the lewd stuff in the overworld, you even have to make a conscious choice of grinding the lewd stuff a bit to unlock more events, there are no "how bad could it be" moments that bite the MC in the ass later.
Summary
Celesphonia is not perfect, nor is it groundbreaking. But it's a very solid female corruption RPGM that tries to do more than just string H-scenes together with some dungeons. I want more games like it.
The writing
The story is perfectly adequate. It strings together all the usual tropes: magical school girl fights horny monsters in horny locations in a mukokuseki city. There are no subversions or unexpected twists, but some subplots are kinda underdeveloped.
The gameplay
Unfortunately, the lewd aspect of the mechanics is mostly divorced from the combat mechanics with a few exceptions. The number of crafting choices is too big for a mostly straightforward RPGM game (a common problem), but the combat mechanics are actually not that bad, it's not pure filler, although it's only the bosses and the secret bosses that present any challenge on normal difficulty in the early game.
The art
The art is crisp and has no obvious deficiencies other than lacking animated scenes. The game is thankfully uncensored.
The lewdness
Celesphonia is very inventive with its lewd aspects of enemy dungeons. There's more to the game than just "the MC progressively becomes a bigger slut" or "the MC gets raped by every single monster", as the MC has to deal with cursed slutty equipment, hypnotic influence and literal pools of semen guarded by tentacles. The only problem is how easy it is to avoid the lewd stuff in the overworld, you even have to make a conscious choice of grinding the lewd stuff a bit to unlock more events, there are no "how bad could it be" moments that bite the MC in the ass later.
Summary
Celesphonia is not perfect, nor is it groundbreaking. But it's a very solid female corruption RPGM that tries to do more than just string H-scenes together with some dungeons. I want more games like it.