This was a cool one. Only complaint is the movement controls can change direction too fast, which makes it hard to do small adjustments without flying off a platform by accident.

This was the first first-person platformer I've ever played, and it was an interesting experience. The game also surprised me because I didn't know Gdevelop could handle 3d games. It was impressive to see the engine used this way, and is definitely more advanced than anything I've made using that engine. 

However, I quickly found out why its such a rare genre. Judging distances, and making precise jumps was challenging, but that's not to say you shouldn't keep working on it and perfecting it because there are some games out there that I have seen such as portal and mirrors edge which are first person platformers and they are highly praised. I think your game is a cool technical achievement but because of the genre it probably needs clever design to work well.