Nice work, it took me a while to get used to the physics but I was eventually able to make it through this game to the end. I appreciate the ambition to add more features to this scene. The climbing timer is a nice feature to add challenge to the game.
There are some glitches that make it hard to get started, when you die at first it seems like it shows the menu scene on top of the game scene, so the buttons are not accessible because the mouse is still captured. You have to escape the scene to get the mouse back and then when you start the level again the mouse is not captured so its hard to navigate. It also means the water doesn't reset so its harder to get through the beginning. I would just reset the level here so you can start from the beginning. It took me a while to understand the walking up walls mechanic, its a bit unusual, so it would be useful to have a part early in the level where you have to do that so its clear from the beginning.
The use of collectible items works well to lead your progress through the scene. It's also nice that there are multiple layers and checkpoints so you don't have to restart from the beginning. And the ending is very clear.
The physics feel a bit slow and awkward, its hard to tell when you're jumping and sometimes the character gets lost. This might have to do with the scaling of the scene, I would check to make sure the player is not scaled and the scene is scaled to match the player.
The scene design is nice, there are a lot of nice details like the water texture and the snow particles. The mix of 2d sprites and 3d is interesting, I'm not sure it works for every component, the character movement doesn't line up with the physics perfectly, but its a unique aesthetic.