His name is Zool, and he is a gremlin-like creature from another dimension. He is forced to land on the Earth, but his sole goal is to attain the prestigious ranking of a Ninja. To do that, Zool will have to travel through six worlds, each divided into three stages, defeat his enemies, and prove himself worthy of that title.

Zool is a fast-paced side-scrolling platformer. The protagonist can run, jump, climb walls, and shoot enemies. Power-ups for Zool are scattered across the levels. These include life-spending hearts, smart bombs, shields, more powerful jump-skill and a twin Zool. This "twin" makes imitates the original's motions a few seconds after he performs them.