puzzles involving cellular automatons in a 2D or 3D grid.

A puzzle involving cells in a 2D or 3D grid, with each cell in one of a few finite states. An initial state (time t = 0) is selected by assigning a state for each cell. A new generation is created (advancing t by 1), according to some fixed rule (generally, a mathematical function) that determines the new state of each cell in terms of the current state of the cell and the states of the cells in its neighborhood.