Here is the same but animated:
Playing with the parameter space:
And the bottom case, animated:
It is interesting to focus on the surviving spot. We can zoom on this area and see what is going on there. The cells have locked into this stable pattern, involving, apparently, two cells only:
excited = @animate for i ∈ 1:30 excite() plotspace(145, 220, 225, 300) end
It is interesting as well to change parameters during the simulation. This locks the patterns into some correlated sequences which give rise to cycles of evolution stationary in space alternating with time.
and coming back to a=20 and cycling over: