Today, I played the "Game of Life" (which sounds like a particularly bad joke to me, but this one didn't turn out all that bad). I had never heard of it before and, honestly, it's not a very exciting game, but you can watch some interesting shapes evolve, following certain rules which are explained on the website.
This was my starting pattern:
And here is a little selection of some that followed:
That's when it stopped - the last two patterns kept repeating themselves as the rules didn't allow anything else to appear.
I had no idea what would happen, but it looks like my large star eventually created four smaller ones. How cool is that! :D