So I played through the demo once, the opening Stage twice, and a bit of the 2nd stage again, and I think my main gripe I came away with was that the hitboxes and how attacks are dealt are boring.
As an example in the factory, the crate throwing conveyer belt boss wasn't fun. The crates as projectiles didn't make sense and I found myself taking damage on them a lot. It feels like you should be able to jump on them just fine, given that they're exactly a full normal jump to land on or go over, but the damage felt unavoidable with them. I ended up cheesing the boss by going to their side and using the invulnerability frames as I pumped charge shots into them. The blue projectiles as well feel super hard to dodge by jumping, and while it seems they're intended to be dodged by ducking, that removes a lot of the interesting back and forth in offense and defense I find in Platformer bosses. I think jumping should be just as good as an option as ducking, as giving more options to play against a boss can drive player self-expression (Aka finding what they find to be the most fun)
The stage design is a little bland, except for when Verticality is involved. That gives me an excuse for the option I ended up using the most (I'm not sure is intentional or not,) the charge jump. Holding down the fire button in the air to fire as a 3rd jump is one of the most satisfying things in a platformer I've experienced in awhile. The closest comparison I can think of would have to be skateboarding games like Tony Hawk, where you hold down the button until you're ready to pop an ollie. If it was more consistent to do, I think it'd be a great tool to have at all times, sacrifing the ability to fight back for the 3rd jump. The dash is very short, and only feels useful if spammed, but I think if just a little bit of momentum could be implemented into it, it could interact very well with the jumping and charge jump. The boss weapons felt a little underwhelming, and the invisibility like a way to just get free damage, but the foundation built here is VERY rocksolid, all it needs is to be further expanded upon.
Im sorry if this review is overly negative, I only played for 49 minutes and those were all the major things that stuck out to me, but I would like you to know that this is extremely impressive. Everything here was made with hope and I'll be following for future updates!