I used the walkthrough mod from another source, when I decide to support you on Patreon and go to the level where I can use the walkthrough mod you provide, will my savegames still be usable with this or do I need to redo the whole game?
If you're talking about Lain's Mod, that locks your saves to whatever version of the game you're playing. Runey has recently added character icons on the new day screen to help people know whose events are ready, so that they don't have to rely on a mod that breaks updating.
I wouldn't recommend using any mods as they will break your saves in the future and it shouldn't be necessary anyway. If you're unsure what to do, that should be made more clear in game.
On that note, I have an idea I'd like to tell you about. The introduction of the icons in the day screen that tell you which girls have ready events is great, but sometimes all is missing is a couple of days. Maybe add that info somehow? Like a number above the head or something?
All events run on this counter, it's usually 2 - 3 days but is adjusted depending on the event. I don't want to turn Harem Hotel into a menu or number simulator, I want to keep it a bit immersive, so I don't feel like numbers here are necessary.
