Click the "Random cells" button or the "Glider", "F pentomino" or "Gosper glider gun" buttons. Then click "Go!". You can re-click any of the buttons once the process has started. To stop it refresh your browser.
This is a non-standard process, based on the idea of JHC's Life. Live cells start with a colour-number of 10. Each time they 'survive', their number stays the same. If they 'die' their number decreases by 1, and continues to decrease by 1 each subsequent generation. If they are 'regenerated' their number increases by 10. Thus gliders leave a track as the move across the grid. The numbers run from 1 to 99 through red, yellow, dark grey, white back to red. Colour 0 is the light grey of the grid. You can change the starting number by editing the javascript.