This is a nice game, though a bit rough around the edges. I like that the orange cube kills the player, as it means the player would need to be constantly on their toes. The level design is good, too.
If there's one thing I'd want to be improved on, it would be to make the screen slightly larger than the stage itself, so the player has space to move the orange box, instead of the orange box instantly jumping from one spot to another. Another way would be to have the orange box collide with the edges of the screen, so the orange box would stay in screen, even when the mouse position is out of screen.