Okay, so you would like your character on some levels to change direction? I have done this in one of my older games. First, you need to add an action to the level and change the gameplay properties (set it to “replace”). When the player collides with it, it will take on those properties. You can change the jump force, so that your character jumps the other way. I think you can change the linear velocity there too, but if you cannot, you will have to play around with advanced moves and objects. If you have any problems just let me know Hope this helps!