Use Boxmen challenges you to get to the box on this barren (but still well drawn) platform land. There are switches to flip and buttons to press. In order to get there you need to use shadow versions of yourself, boxmen.
They will mirror what you are doing - if you're standing: they stand, if you're jumping: they jump, crouching: they crouch. Get them to do the work that you can't, and get to that box.
Run and jump and duck with the arrow keys, then use shift to create a new versions of you - to use a boxman.
Think about the timing. If you set a boxman going one way, will they give you time to get to where you need to be.