You control a character armed with a giant blade, the SplatMaster3000, and your goal is simply to exterminate various hostile blobs of goo called Glooples.
The game has 2 main play modes and a Practice mode:
In the first mode, Single Nest, you must kill a specified amount of Glooples as they get increasingly difficult and more numerous, where bounty is a secondary goal.
The second mode, Bounty Run, consists of an infinite number of Glooples where the goal is simply to rack up bounty and survive for as long as possible.
In the Practice mode, you can select Glooples from list of those you're already encountered and the game will only send those types of Glooples at you.