Zas gameplay is done in a style similar to Gradius and R-Type.
Players proceed through the game; shooting enemies while dodging obstacles and collecting power-ups for their shooting weapons. The game uses the basic configuration for the ship's control; with one button doing the shooting. As a complex scrolling shooter, this game attempts to emulate multiple dimensions using the limitations of the Game Boy console. The parallax backgrounds and elaborate detailing in the sprites help to create a unique Game Boy experience; any distinctions between the scenery and the bad guys are clearly shown through different shades of the same color.
A higher degree of difficulty exists in this game as opposed to most Game Boy scrolling shooters of that era. Timing is essential to clearing most stages and for defeating the end-level bosses.
There are five levels in the game. While the first four levels can be freely chosen, the fifth level in the game is unlocked after finishing the first four levels.