Implementing the Conway's Game of Life on a hexagonal grid could be a fun idea. With a slow enough turn clock, you probably don't need a start/stop button, and can just mash a pattern in with one or two hands quickly and see how it evolves. Another plus is that there probably aren't too many famous hexagonal lifeforms, it would be a fun game for all ages.
This is a great reference for starting to work with hexagonal grids: https://www.redblobgames.com/grids/hexagons/