Now there's an idea. A section with platforms, so you can see a lot where enemies dance in sync and they shoot in sync with the beat. I have no idea if I will have time to do that, but I will have to try it out. For time being I plan to work on pure gameplay features alone to get to proper vertical slice. Then I might work on music system a bit.
The game is using multithreading a lot. Because of that it can hit 90fps. The bigger the level, the more workload there is - all NPCs moving around, etc, but there is a lot of cheap optimisations, ticking some stuff every second or third frame etc. With 90 fps some enemies have logic running at 30fps. Which is what is happening for some of the normal games ;)