HAhaha i just figured out what you have to do to pass level 15!!! Firt throw 2 grenades then run to the wall direction and jump, when you are jumping the granades will explode and will throw you a bit more far. Hope this help you guys also >D
At level 18 frist use the mech to pass the acid, then at the end use the Kinect Module "C" to rotate and position the buggy as you will be able to use it to gelp you jumping the walls.