The egg is too big for the characters to hold. The only way to move it is by pushing it. Various obstacles are in the way of course. The game features 20 different levels with each some unique puzzles to overcome.
The characters are controlled using the keyboard. Each player can move left and right, jump, aim up and down and has an action button which is context sensitive.
Players have various ways to interact with the environment. They can pick up and drop wooden boards which can be used to create makeshift bridges. Levers can be pulled to open doors or activate elevators.
There are three different power-ups that can be used to solve puzzles: Gunk, Blast and Spike. Gunk is shot with the "Gunk Gun" and is a sort of glue which can be used to glue objects together. Items that can be glued include boards, the egg, the players, elevators and the terrain. Blast invokes the singing power of the blobs. Their screech will cause a shockwave which blasts away any player, board or egg. Spike gives the players the ability to stick to dirt walls. It can be used to stick to walls and ceilings to reach otherwise unreachable locations.
Most levels have multiple solutions. Usually possible solutions are easily made up, but less easily performed. The physics allow for many possibilities and require both players to time their actions very strictly.