Just watched your stage demo and I'm impressed man! Now there is actually a reason to use the left-right shimmy when climbing. I always thought that was a nice detail in the arcade, but there was absolutely no in game use for it.
One suggestion, and should be a pretty easy fix - you need to separate the background layer. Even if you are going for authenticity, it just looks awful to see a far away night sky in perfect snyc with the foreground as you move.
Multiple layers were the norm for arcade games long before Double Dragon's day, and the fact they used only one was pretty hokey.
DC