Some high quality art and soundtrack right there!
A few gripes of mine: the movement speed vector seems to be multiplied by the direction player is facing, including the rotation on the Y axis (up and down). That makes you walk slower when you look up or down.
Also, in the beginning I couldn't easily figure out how to climb the mech, I spent like 10 minutes running around it and climbing ladders, and in the end I still couldn't, pressing E at the prompt 'exit/enter atlas' doesn't seem to do anything for me.
And you can noclip through the back door.