What is the point of this game?

Well, if you bothered to read the instructions, mate, you'd know that you have to:

Avoid the little bunyips (pronounced "bun-yips") and collect as many boomerangs

and bunyip blasters as you can, and reach the final level of the Dreaded Toxic Bunyip!

You must then defeat this Big Bunyip in order to earn the bunyip icon :)