itch.io

I wanted to address this properly while also speculating what Deltarune's version will be like, so I made a big thread on my socials about it, here's the link: https://bsky.app/profile/ezioeagle.bsky.social/post/3lq5tkddj4s2n
tl;dr maybe eventually as alternate difficulties, but not to played simultaneously since I'm pretty sure that won't be how it works in deltarune because of how hard it would be, and because looking at the score and max combo, it doesn't seem to increase when his notes are hit, so I'm pretty confidant that only Kris' part is controlled by the player there. Ralsei's and Susie's parts could be alternate difficulties though, with Ralsie's being an easy mode, and Susie's being a hard mode that's unlocked once you beat Kris' (which is why it's crossed out, not just a joke about not being able to control her)