One plug - in i'd love to be able to use is that of spline pathing for sprites.
the sprite follows a path and rotates according to the angle of the spline by the following 2 means :
rotation by the application (hardware/software rotation)
rotation by animation (object is drawn at varying angles)
rotation by animation is necessary for things like isometric viewpoints as sprites have to be drawn isometrically and wouldnt look right if rotated by the application.
the paths could be divisable by specific groups so that specific path based objects could be locked to scrolling layers, for example the difference between a tank and a helicopter, because say the tank could go under a bridge overlay, and the helicopter would fly over it.
endpoints of the spline could be assigned to either destroy or stop the sprite.
hopefully someone may deem this a worthy addition.