Gorgeous looking game and very atmospheric, but über-punishing level design.
I see others have mentioned the jump-dash and here's my take: the jump-dash is a little tricky to use because, unlike a typical jump or double-jump, you have little to no time to do any course correction after the dash completes, especially when jumping to a higher elevation platform. It means that if you overshoot, you're done. If you overshoot on a jump, you can let off the jump and have some time to move left/right to accommodate. (I did find that I could mitigate that some by simply dashing and jumping at the same time, which in your mechanics creates a sort of boosted jump instead of a jump and air-dash.) Anyway, all that's workable if you build the level around that lack of control. Instead, literally the first time you have the user try the dash, you're forcing them to land on a one-tile platform. Not too much later, you have a similar jump, but it's somewhat far from a reboot station, so you have to do three or four jumps, fight several enemies, then overshoot the dash jump, then do it all again...and again. I'm of the opinion that sort of stuff should be much further in the game after the player has had plenty of time to use the abilities, get used to feel of your game's controls, and have practiced several similar jumps in less punishing situations.
I feel like I've sort of ranted on this, but it's only because the rest of the game feels sooo good that I was upset that I couldn't face playing it. I really want to learn more about the world you've set up, the melee feels nice and crunchy, the post-processing is tasteful despite how much of it there is, and the music and sound design is top notch.
You guys really did a fantastic job putting this together. Just give the level design some more love and you'll have a fantastic piece!