I usually avoid rhythm games but I do like dungeon crawlers so that's the part I'm going to speak to.
You've got a really good base done here. I was a little confused what specifically caused me to take damage and how I was supposed to defeat the snails. I had a snail spawn in one of the hallways and I couldn't get passed it. I think adding in some weapons or other ways to fight the creatures would help. And use syncing to the rhythm to do more damage or something. I'd personally brighten up the walls of the rooms a bit just to give a better idea of the bound.
I really like your music, it's good for keeping the beat to.
All in all, I think you have a very good start here! Good luck from here!