world/movement_style=SIDE_SCROLLER //MOVEMENT BECOMES SIDE-SCROLLER LIKE
world/movement_style=DIAGNOLS //ALLOWS PLAYERS TO USE ARROW KEYS FOR DIAGNOL MOVEMENT
world/movement_style=DEFAULT //THE CURRENT WAY DM HANDLES MOVEMENT WITHOUT ANY MODDING
SN: For side-scroller mode you can also add a new var for atom/movable that will set there depth/heights of their jumps.
atom/movable/jump_height=32 //IN PIXELS???
I assume this is the same problem plaguing your side scroller; not being able to move and jump at the same time. By using key-down and key-up macros (instead of repeating ones) you can create loops that will allow the game to properly understand multiple keys being used simultaneously.