The simple rules of Life made it obvious to write computer programs that play it. There are lots.
Here’s one that I made. The link opens it in a new tab.
Click a cell to toggle it alive or dead.
Step to the next generation. Press again for the next, and so on…
Fast forward will play automatically. There is a slider underneath the toolbar to control the playing speed.
Try out the grid you made on your whiteboard. Was your next generation correct?
Stir up a random soup of cells and see how it evolves. Look out for any interesting patterns or evolutions and see if you can make them happen on their own.
Clear the grid and start again.
Choose your own colour for live cells.
Toggle between small and large grids. Warning: this also clears the grid.