I've reached chapter 3 on Hard as of this writing

It's essentially three rhythm games in one.

First, we have the Rift stages, which is essentially 3-button Guitar Hero. The gimmick here is each "note" has their own way to move about on the map. It's a fancier way to represent beat maps, but at the end of the day it's still hitting the right notes at the right time. I'll be honest, as long as you can "make sense" of the underlying beat map, you won't have to think much about how the mechanics and timing of each enemy works.

Second, we have minigames. It's Rhythm Heaven games. Sometimes the prompts are thrown at you like a reaction-based game more than a prompt-and-response game. On the other hand the timing is quite lenient. It's a simple and effective design, and I wish there are more games in here.

Finally, the boss fights. It's Punch-out but on a rhythm. You memorize the attack patterns from the animation prompts, dodge accordingly and attack. I strongly recommend to play these stages on HARD, because on normal difficulty they show you when to hit which dodge button on the screen, which makes you skip the entire pattern recognition part, thus vastly reduce the enjoyment of these fights. A novel concept, though I have to say it's still mostly Punch-out, and the rhythm game part didn't elevate the gameplay more than that.

All the songs are certified bangers, Most of them are remixes of songs from CotND (shout out to Jules, your guitar rocks!) plus some new ones. If you like metal, I think at least a few of these songs will be on your playlist