Flip is an EsotericProgrammingLanguage created by Rune Zedeler and Erik Søe Sørensen.
A Flip program consists of a two dimensional grid of squares. At each square an object can be placed. The computation is performed by simulating the movement of one or more balls in the grid. Each ball contains a number, and can interact with the objects in the grid. The objects are walls, sluices, number generators, tarpits etc.
The official home page is http://www.daimi.au.dk/~eriksoe/Flip/ .
The following program, which is animated on the language's home page, prints HelloWorld.