You can also download the Java version, which has more advanced features like an iteration counter, full screen size, and colored trails!

RULES: 

Use the left mouse button to place or remove initial cells. Use the scroll wheel to change colors. Press space to start/stop the simulation

For an alive cell

• A cell with ZERO or ONE neighbor dies, as if by underpopulation
• A cell with FOUR or MORE neighbors dies, as if by underpopulation
  
• A cell with TWO or THREE neighbors survives

For a dead cell

• A cell with THREE neighbors becomes populated

Additional rules for this version

• When a cell becomes populated, it inherits the average color of its neighbor