i know the game is still in early alpha so some of these are probably already planned but just in case im posting these ideas.
potion index
so the alchemy system is cool but i think there should be an index of discovered potions that tell you how to craft them. discovering potion recipes by experimenting, pulling them off of raiders, or buying recipes in the shop.
raider difficulty level
in the tutorial it says invaders get stronger each day so if that's actually the only thing that effects the raiders i think there should be a counter underneath the day counter that tells you the current level range of raiders. also the ability to force a stronger enemy to spawn in probably using the alter to summon a hero.
character creation and clothing
i play as a male character because i like to self insert myself into these type of games but its kinda hard to when 99% of the clothing are woman's clothing and the walking/running animations being clearly only made with feminin characters in mind also brakes my immersion im trying to play as a dark lord with a harem not a femboy, so more options for character creation with having more normal options for male characters would be nice.
also clicking the clothing options should open a menu to select what basic clothing you want your character to have to allow more customization.
the ability to rearrange room layout.
i have created quite a few saves just because i ended up not liking the way i built the rooms so being able to pull off a room and place it in another location with a build menu can allow me and other to experiment where they want things to be, also this would change the way relocating the thrown room since you could drag and place it where you wanted. relocating a room would probably cost the same as relocating the thrown room.
of course would need countermeasures in place so we cant move the entrance or just cut off the path to it.
leveling
currently there is not really any way to really train an npc or your character, since during my time playing the game i found that i have zero clue on how to level up one of my servants the only reliable way to do it is to spam use prismatic shards by crafting a bunch of them which doesn't feel like that's the intended way to actually level anything so a way to actively level.
content filters
basically just a way to turn off specific stuff you are not into. example is the futa characters, there is currently an unlock you can get that allows them to spawn but i think that should just be an option you can tick a box for in the settings, could also add an adjacent slider for frequency or something like that.
servant hierarchy and groups
the ability to create specific groups of servants to help with management or to have specific servants as favorites. an example you could make a group for miners where if a servant is assigned to it they will automatically look for an empty mine type room to work in additionally you could appoint a servant to a manager role. currently the only way to mark a character as a favorite is to allow them in your court this future can also allow you to create a group named favorites so you can more easily find them since you might not want them to be in the court all the time. of course you can freely name the groups whatever you want as well as how much power they have in the dungeon.
over all i like the game and want to see where it goes.