Birth/survival counts. Try B36/S23 (HighLife), B3/S012345678 (Life without death), B2/S (Seeds). Cells are coloured by age.
Each tick computes the next generation from the bottom row and scrolls the board up, so you see the last eight generations. Rule 90 makes Sierpinski triangles from a single cell; 30 is chaotic; 110 is Turing complete. Press pads on the bottom row to seed.
The ant turns right on a lit cell and left on a dark one, flips the cell, and steps. Press a pad to flip cells in its path; hold a pad for a moment to move the ant there.
F and G draw a step, + and − turn, [ and ] push and pop the turtle. The turtle walks the expanded string one command per tick, wrapping at the edges. Press a pad to restart the turtle there.
Press pads to seed. Logo: play / pause. Right column: speed. Arrows: ↑ step once, ↓ clear, ← random, → next mode. The board is the world; the screen is just a bigger window on it.