Developer: Game Freak, Inc.
Yoshi Game Manual
In Yoshi, the player is tasked with clearing monsters from the on-screen playing field. The monsters fall in from the top of the screen to build vertical stacks; the player must prevent a stack from growing too high such that it exits the play field. In order to so, the player swaps and moves the stacks about such that falling monsters collide with identical monsters stationed atop the stacks, causing them to be removed from play.