The idea is good - I think this could be a really good game, and overall I liked the mechanic, but it got boring quickly. I think it just needs some more game elements, and honestly a soundtrack would make it more engaging certainly, especially if it was per level. I would add a time limit, or a limited amount of "ink" to draw the platforms with. Make the bullet a little faster, and bind restart to R because honestly my platforms were always wonky and you cannot undo.
Cool game though