Your game is currently very buggy at the moment. I just float upward after a while. I don't fall when I walk off an edge either. The combination of these two bugs do not allow me to progress through the game. You should also add a jump and crouch command like in the original Contra. They would really add to the gameplay value.The game needs a lot of fine tuning. The enemies do look pretty cool though. Keep working on it and I hope to see the finished version.