Use WASD or Arrow Keys to move. R to restart whichever level you're on. On level 3, if you get sent to the top of the rectangle, press r.
So this is basically the easiest platform ever. I made this as a passion project and there's not much to it. Thanks to "El Rincón de Primaria" on youtube for the jumping, ground, and gravity tutorial. Thanks to the scratch Q+A Team for showing me how to do the shadow effect.