Totally. I know that making it with Grammer is possible, and we both have done it (well, I need to get that buffer storing thing figured out first). So next step is speed. Yes, do it!
How are you going to include other cellular automata?
And wow. That prime sieve is a literal sieve. It take a big pile of numbers and takes out all of the primes. Mine takes one number at a time and sees whether or not it fits in the holes (of the sieve

).
So what good does it do to have the numbers on the graph? Will you then use a second program to figure out which number each corresponds to, then store them to a list? Or is there no purpose, just to say you did it? Or a test for a programming language?
EDIT: I don't know why but I've never been smart enough to just say "If pxl-Test(A,B" instead of "If pxl-Test(A,B)=1". Cool! New memory saving technique!