The blue screws contain singular hammers for the secret NPC menu, the item box contains a fire flower (replaces the oil barrel), and there is a hammer suit up top...or is it really the top?

Screenshot:

Download here (FIXED)!
Red girders and blue ladders made by me, blue screws made by Redigit.
If you have any feed-back (including a solution to the fact that the name for the level in the battle level menu shows up invisible/blank), feel free to share it. And, if you really want and can, post a video of you and a friend battling it out on this level!