This felt pretty good for a third game! I enjoyed the level design and pacing, and the movement mechanics were fairly solid.

I found myself wishing that there was some "camera slop" to make the camera be more stable when making small sideways movements. There are many different possible approaches for addressing this sort of thing. In Godot 3.x, there is an InterpolatedCamera class that might help with this. It will be removed in Godot 4.0, but I'm not sure what it's being replaced with.

I also found that there wasn't quite enough air control to be able to comfortably/reliably execute some of the actions that the game was asking me to do - in particular, I would have liked to be able to stop my sideways movement more precisely - some games do this by reducing sideways movement a lot when the direction button is released.

I also found it difficult to fall off a ledge and quickly slide down the wall. The game often offered another wall to jump onto first so that a wall jump back could put me onto the wall that I was intending to slide down, but the ability to quickly turn back when falling would improve the sense of control in general, I think.

The first checkpoint seemed to be behaving a little oddly. I activated it from below and respawned above after dying, effectively skipping a spike obstacle without having to successfully perform the movement challenge that the level was asking for.

I don't recall which level it was (possibly level 3 - it's the one in this screenshot), but I felt like I would have appreciated a checkpoint at the top of the wall jumping section where spike obstacles would pop out. It was a difficult sequence and the sense of accomplishment for completing it was diminished when I had to it many times after making mistakes with the triangle enemies above.

Overall, the presentation of the game was cute and fun and engaging. I love the way the player character's legs communicate directional movement. There were a number of grammatical mistakes in the text, which might be worth fixing, but it also adds some extra personality to the narration.

A sound effect and visual effect for activating a checkpoint would offer some positive reinforcement and make it clear when when it has been activated.

It might also be nice to allow the player to press jump to skip the pause after dying. When dying many times on the same obstacles, spikes, or enemies, that pause does not communicate anything new, and can add to a sense of frustration.

Last, but not least, O and P seemed to do the same thing (O is meant to stop the music, but it just started the next track).

I hope some of that is helpful and that you had a positive experience with Godot. Thanks for doing a Linux build! :D