I guess you need a long layout where you just run across like a platformer, keeping the scroll to on the player and if you stop you die. You could mimic it by possibly doing when right key is pressed down, have the background scroll in bullet behaviour like you have there with things coming at you while the player character is static, so you are in control of the level moving. So basically whenever right key is down the bullet behaviour is enabled on the background and floor, then you spawn obstacles randomly, while your character has a running animation.