Ok, wow, just wow, this one left me speechless.
The puzzle aspect may not be for everyone, and I almost gave up on solving the first one, but I powered through and after that, this ended up to be the best TWO WHOLE HOURS (gamejam game!) of my week.
This is an experience you should have for yourself, so it's a little hard to write a review. I will be trying to keep things spoiler-free.
What I will say though, the way everything blends together is gorgeous. You always get a double reward for solving a puzzle, both the gratification from solving the puzzle itself, as well as the newly acquired ability/change in the environment that completely changes either the way you play or the world around you. The only exception to this is the last puzzle, since you can't play the game any more after solving the last puzzle. :(
While the graphics may be a little lacking, they are not the main focus and even so, the world feels varied, has sub-areas and succeeds to be pleasing to the eye towards the end. And every other aspect of the game is nearly perfected, especially the level design and the puzzle design.
The sound design is very pretty as well. Background music and the SFX fits the game perfectly..
Now, to the downsides (and some minor spoilers):
There is a spot in the game where you can softlock and have to use console commands to escape, as well as a certain moment which can cause your save file to corrupt. (This is related to the gamejam version of the game specifically and has already been fixed locally according to the developer)
While things like that can happen during short development phases, this breaks immersion quite a bit, and if unaware of the issue, you can just randomly lose all your progress and be forced to either rage quit or replay everything again.
The way you can fall into water from a height and hit the floor spikes, while realistic, doesn't feel very game-like. Usually, in games with water, all vertical momentum gets cancelled when you drop into water to prevent such cases and I died at least a few times because of that assumption. The upside of that is that you don't feel all that floaty while underwater, which actually makes the water section a lot more bearable and pretty fast to navigate.
The graphics. If the game was a tad prettier it would easily be breaking top 10, but people tend to click on pretty thumbnails and see pretty graphics and go "waoh", while hidden gems like these end up being a lot less popular than they deserve. Since it is a development build, it is easy to forgive, but to me, this felt like a completed game, so for the final release, if the graphics get an overhaul the game WILL get big, mark my word.
The only sound effect that was throwing me off is that of a projectile hitting a wall, sounds a bit like a wooden drum, doesn't feel like it fits.
If you're still reading and aren't the developer, GO PLAY THE GAME! And if you are the developer, thank you so much for making this!