Split is a cellular automaton designed to simulate embryological development. The cells of a hexagonal grid represent cells in a developing multicellular organism. A cell's colour represents its cell type. Cells of different types may replicate at different rates and may change type in response to the types of cells immediately surrounding them.
A single hexagonal cell is coloured initially. By clicking "Split" we can make this cell divide, colouring one of its adjacent cells.
By clicking on a cell, new cell differentiation rules can be added for that cell type. Each rule states that given a particular set of surrounding cell types, a cell will change colour.
A cell type's replication rate can be set so that it replicates every step, every few steps or not at all, or so that it will disappear ("apoptose") at the next step.
By combining rules, complex patterns arise as division steps progress: