Liquid is a fluid simulator that takes advantage of the unique accelerometer controls and multi-touch interface available only on the iPhone and iPod touch. Tipping the device will cause the liquid to flow in the direction of gravity, where it pools as waves are reflected and lightly roll back up the slope. The multi-touch interface allows the user to press down on the fluid to control the flow.
Along with utilizing accurate wave equations, Liquid features realistic optical refraction, so that the texture underneath is distorted when liquid flows over it. There are twelve different color schemes available, one of which is completely transparent to accentuate the refraction effect.
To access the available colors, click on the information button in the lower-right corner. From there you can access twelve different textured backgrounds, as well as a slider control for the speed of the simulation.