Use the cams:
To see what the others players are doing in all the level, you must
place sprites (x!y) with the texture of the cam (the first), where x is
the angle of rotation of the cam, and y a value wjo is the number of the
cam. You must rotate the sprite to the direction you want to see.
Where you want to place the screen, put a sector of the size of the screen. The back of this sector must have the texture of the brake screen (texture number 501), then, in the middle of this sector a sprite (y!0) with the exactly same size than the sector. This sprite must have the texture of the screen(texture number 502), where "y" is the same number as the cams t see in this screen (many cams can have the same number), and then you put a glass in front of it. You must finish in 2D mode: presse the [B] and [Ctrl-H] key on the sprite of the screen and on the glass, so it must broke when you shoot it.