Flakboy is a physics game where the player places various kinds of deadly traps to damage an immortal creature called flakboy in a weapon testing facility. The goal is to strategically place these traps to get the most damage on flakboy using the given budget.

First, the player must place a duck box to scare flakboy to the opposite direction, where he will be hit by the first trap. After being hit once, flakboy turns into a ragdoll and is completely relied on physics to move around. The player can use mines, spikes, gun turrets, missiles and trampolines to both damage and move flakboy so he can be hit by other traps.