So, I tried this game 2 times.
First time I didn't quite understand the mechanics from the tutorial, partly because their peculiar names. I managed to defeat one boss, but then was bored by counteless defeats by overall seeming randomness.
But somehow I wanted to give this game a second chance, I guess because I felt a bit bad, that I didn't try to enjoy it fully. And here is my feedback:
1. So, on second time I got how basic mechanics work, though some abbreveations weren't introduced, like DP, SP, 3DI (3DI thing meaning I've only got while was writting this review), so some mechanics were still a mystery; where bug with incorrect text for using GRR makes it even worse, like it should increase your flow by 10 and 3DI by 5, but instead game says that it increases your flow by 5 and 3DI by 0 after you've used it.
2. You can outheal your max hp https://ibb.co/PnB136S with resting for example, dunno if it is intended.
3. My first encounter was with "a friend" https://ibb.co/d4pCxcp6, but game counts it as a battle, which is kinda strange. Another moment, I would say it is a bit inconsistent, how we don't know the enemy encounter and mark it with "????", but we know for sure we will meet "a friend" on another path though we are going there for the first time. Shouldn't it be the same like with the enemies? So if after rewind I see the house there, now I know who lives there and know it is not an enemy and etc, but for the first time I can't know that. Then instead of "a friend" perhaps could use another words, like "a house", "a stranger" so player can make better decisions.
4. In some places Rectangle is mispelled https://ibb.co/dJjtW22D
5. So after house my next encounter was vampire driller, I've lost and strange things started to happen. On back home I got this message POSSIBLE SPOILER ALERT (dunno if it is actually counts as a spoiler, and if it is that heavy spoiler, I can remove link if you want), so like game decided, that I've actually completed the game, instead of losing a battle :D.
6. After the rewind everything was as usual, until I met him - the bald old guy. So I peacefully defeated him and after that my game was cursed. On next encounter I met him again, but after I charged my drill, encounter instantly abrupted and I got usual rest screen after battle. Then on next encounter I met him again and again and again, and each time I had the same battle skip; until I think I got to the last Inferno layer where, I'm assuming i've met one of the winged semi-final bosses, but again, instead of actual fighting after drill charging I got message, that I reached the center of the planet with tree. (I can send you screenshot if you want, I've though perhaps it is a bit too spoiler-ish to post it here). So after that, i'm assuming, instead of final boss battle I was able to just continue go deeper in Inferno as usual and all battles were like "I use drill charge" - "Battle instantly abrupts in the next screen and rest screen with rock is shown". So game was in general heavily broken, like also sometimes when I encountered some enemies, on their turn they turned in other bosses. And etc, so text and images were desynced, except candy-meetings and resting.
7. Vampire-driller iirc doesn't have any fight introduction, and some other fights don't have proper introduction as well. This felt a bit strange, like we just fight with everything we see without any purpose for it, except "friends". So would be nice to know what was the cause, since we don't fight with some brainless slimes, but with other humans (?). But dunno if it is somehow was explained in boss lore books (?), because I didn't manage to read them.
8. I would remove annoying spiral thing completely. Iirc it doesn't have any explanation lore-wise (like we don't ask the Keydrill about it after the first fight, so it could explain what this thing is and how it works; but just accept things as they are). And what is more importantly it adds many frustration with "lemme set your 2000 RPM to 500", which is happens quite often. And that's kind of random is kinda frustrating, because you can't really heal and you need to waste your turns to accumulate RPM again, so it is kinda a run killer, which you never wanna use.
9. Poison boss. Dunno if it is intended, but they can't kill you, because no matter the poison rate, poison damage depends on your current hp, so when I gave up and wanted to just die to him to reset the run, he dealt to me 0 damage, when I had 1 hp. And I couldn't kill him either, because my charging was super debuffed and was like 37 RPM for charge iirc. So it was kinda super troll fight, were we both couldn't kill each other. (well, in theory I guess I could win but it would take very long time because of low charging rate)
10. In general fights felt a bit too random-ish, like again, with poison boss I missed like 5 times in a row iirc and like I can't do anything with that, cuz I don't have some kind of accuracy buff. Or when you can block enemy attack, but suddenly another enemy attack becomes unblockable and you should've used dodge or parry, but you couldn't know that. Like yeah, for some bosses I think you can use some consistent strategy, but not for all, unless you learn all their attack patterns, which can be a bit time-consuming.
11. Resting and candy-meetings scenes felt kinda repetative after some time. But dunno what really can be done here, like it was particularly annoying to skip candy-boy lines, because you always want to take candy, from what've understood, so you like have to manually skip them everytime.
12. Art looks cute, but style seemed to me a bit inconsistent, like if you compare candy boy and man with a big drill from your screenshots. But maybe I have that feeling cuz of a bit different dithering. Also perhaps fights could look more engaging with OMORI-like battle animations.
Overall, good job on your game; in addition to default art, music and game logic you, I assume, had to spend a lot of time on writing, which may be quite hard to polish, and you still managed to finish it to playable state. But there is still room to improvement. 🙂