@MatrixWorld : Yes, slow while scrolling. That is because this scrolling engine scrolls the "universal" image, which, because of its size, means a lot of cpu activity. My Scroller class (found by way of my "Scrolling Tutorial" scenario, can be used to scroll only actors, which would pretty much solve that issue. Search "Scrolling Tutorial" to locate.

@stylus, if your game is running with the menu up, then you probably have your menu in the same world as your game. Note that the world FabriG has provided code for is for the menu alone and has nothing to do with the playing of the game itself. The "enter" or "space" key with option zero will proceed to another world (BackgroundLvls) which probably still a world where game-play is not yet arrived at. A specific level world would be arrived at from there where the level is played out.

@Kizetsu, start a discussion thread on your issue. Provide your attempted codes (complete classes) and an error trace from that particular code. Help can then be provided.

@Wkot, to prevent the Who actor from sinking below the bottom of the screen, its y-coordinate must be kept below a point in the world that is half the actor's image height less than the world height. That expression gives that y-coordinate of the line that the center of the actor is not allowed to go beyond in the downward direction.