Side-scrolling beat-em up next! :)
You could also add some code based on y-axis for the origins of obstacles, so like streets of rage, turtles or similar, you could hide behind stuff, collect power ups. The only downside would be trying to sort z-axis if you want things like doorways etc.
You'd have to check whatever the character was overlapping was lower or higher on the y-axis, and if lower (on the screen) set the character to the bottom.