Oops, the trees weren't updated.
The original question was about the rocks, flat or none flat.
http://www.youtube.com/watch?v=8gBEXMLTPt4Anyways here's a video of how the levels of the game transfer from pixels to 3D.
To explain the lines in the video, I think I'm changing the sprite from the very edge to the back of the line.
Ontop of level are like lanes
____________________________Foreground
____________________________Sprite path
____________________________Background 1
---------------------------------------Background 2
[ SKY BOX ]
Maybe this thread should be moved to Low Spec Art