itch.io

Hi! You're right, i should have added some form of a tutorial that explains this mechanic, my bad. But in short, you can "detach" your head from the body by pressing shift (the same for returning to your body). If you enter ghost mode, your body stays where you have left it.
In ghost form, you are invincible to spikes. You also pass through thin walls/semi-solid platforms, and push boxes around.
Meanwhile your body is fragile, so you have to avoid the spikes. It can walk on the semi-solid platforms and interact with doors, so you have to bring your body with you to get to the next level ;)