Mario Clash(1995)

Mario Clash is the first 3D stereoscopic Mario game released for the Virtual Boy. The game is a return to the style of the original Mario Bros. To progress through the game, Mario must knock enemies off platforms using Turtle Shells. There are always two Koopas; if one gets knocked off, another one takes its place. Many enemies need to be hit from the side, thus Mario must throw shells from the background to the foreground and vice-versa in order to knock them off.