Arrow keys to move about, SPACE to jump, Z to shoot, down arrow to use the morph ball (once you obtain the powerup), and press SPACE while touching a wall to stick to it (once you got the powerup) This is an early release and there will be loads more stuff, like a better engine and a more open world so check regularly for updates. Also, this is a reimagining, not a remake.
I made most of the music myself using Beepbox except the title screen, which is from Metroid Fusion and the music in the mossy part of Brinstar which is from this project: https://scratch.mit.edu/projects/440827286/