Hello, love the game has a good loop. Though I have run into a couple issues and thoughts for future development.
Starting with issues. after closing the game from the first time I played it, then opening it from the application and loading my save. It seems the online selling option stopped working for me. I would select slot one and it would close the choice box but never load up the dialogue box. Effectively soft locking the game which required me to close and re-open the game. Differences between first and second play is I chose to use a controller, however the issue persisted even with the controller disconnected.
This lead to me second issue and suggestion. There should be an NPC in the town that can take Healing potions. Currently there is one red potion buyer and the rest are Mana. Not being able to do the request sales stuck me with a bunch of Healing potions I could not get rid of.
Third issue after activating the code in the green and red slime cave, then buying Mana storage lvl 4 the blue slimes seems to stop spawning. This could also be an issue triggered by a separate cause that I got knocked out in the G&R cave, spent mana in the tower then went back to the blue cave without "sleeping". When I entered the blue cave the character did the waking up from being knocked out animation and there were no slimes in the cave. This issue persisted no matter how many in-game days passed.
This leads me to a suggestion. At a future point in the game, probably once you are more well established. It might be a good idea to be able to farm specifically Blue slimes outside the tower. Since blue mana seems to be needed and used for a lot of things it gets tedious to constantly run back to the cave to refill on specifically that one.
That leads me to a nit pick, I really hate the long walkups to the caves, it is neat with the lighting change but annoying after the xth time you have to do that run, I would rather just be put right into the cave map.
Another suggestion is a way to drain specific mana colors to either get rid of them or store them (Milking scene or something) It is easy in the second cave to get colors you don't want or get full up and need a blue for something but can't get more. This would also be helpful in the future if you add more colors that can be obtained.
Love the sizes she gets to in the game, my only suggestion is we can always go bigger.
Overall very fun game and looking forward to future updates.