Brian's Brain
=============

https://en.wikipedia.org/wiki/Brian%27s_Brain
https://en.wikipedia.org/wiki/Brian_Silverman

> Brian's Brain is a cellular automaton devised by Brian Silverman, which is
> very similar to his Seeds rule.
>
> Rules
> -----
> Brian's Brain consists of an infinite two-dimensional grid of cells, but
> unlike Seeds, each cell may be in one of three states: on, dying, or off.
> Each cell is considered to have eight neighbors (the Moore neighborhood), as
> in Seeds and Conway's Game of Life.
>
> In each time step, a cell turns on if it was off but had exactly two
> neighbors that were on, just like the birth rule for Seeds. All cells that
> were "on" go into the "dying" state, which is not counted as an "on" cell in
> the neighbor count, and prevents any cell from being born there. Cells that
> were in the dying state go into the off state.