In the game, the player must guide a puddle of fluid to its target destination by tilting the scene, not by moving the fluid itself. They must work with physics: friction, momentum, and the unique properties of each type of fluid and environment to send as much of each puddle past such obstacles as fires, rifts, spills and other, through environments like pipes, plants, laboratories, a human body, a sewer, a rocket, a foundry and a power station. The experience is based on physics, making the fluid motion realistic. Source: Wikipedia, "Puddle (video game)", available under the CC-BY-SA License.