Start by adding a drawing canvas object. This will not need any behaviors or instance variables. Make sure to set the image point in the middle! Next add a tiled background instance called "solid". Make it a 32x32 tile such as:
Obviously this will need the 'solid' behavior. Next add a background. This can be a tiled background or sprite and has no behaviors or instance variables. After this you will need the keyboard instance for player 2's 'WASD' controls. Finally add a player. He only needs the 'platform' behavior. Duplicate him for player 2.