Fun!
I wonder if eventually, when you run out of other things to do, you could maybe make Susie and Ralsei playable?
This of course could just be cosmetic only, or be a different chart (like they play in Deltarune), but I was thinking maybe it could instead be 4-key (Susie) or 1-key (Ralsei) charts instead?
I know that would be a large undertaking, but I think it would make it appealing to a wider player-base, not to mention add some more variety since there's no level decoration or VFX possible. Of course not every level would have to have 4-key and 2-key and 1-key charts (that would be an insane amount of work, especially for you).
Just a suggestion! Looking forward to seeing what's next in store for this game regardless :)