Scrolling shooters are a subgenre of Shoot 'em up games and include vertical or horizontal scrolling. In a vertically scrolling shoot 'em up, the action is viewed from above and scrolls up (or very occasionally down) the screen. This has the advantage of allowing complex patterns of enemies, as well as allowing even simple graphics to function convincingly. Vertical scrollers are best suited for arcade machines with tall screens; screens used with home computers or consoles tend to be wider than they are tall, thus are less suited to vertical scrolling. The other main type of scrolling shooter is a "horizontal shooter" or "side-scrolling shooter", in which the action is viewed side-on and scrolls horizontally. A small number of scrolling shooters, such as Sega's Zaxxon, feature an isometric point of view. Others dispense with scrolling altogether, instead using a flip-screen device: when a player reaches the edge of the screen, a whole new scene appears at once. Some shooters may feature multidirectional movement ("multidirectional shooter"), generally with a static screen.