Conway's Game of Life online

A Game of Life simulator that runs in your browser

The Game of Life has no players. It is a grid of cells, each alive or dead, that changes on its own from one generation to the next by a very short rule. You draw a starting shape, press "Start" and watch: some shapes die out, some freeze, some blink and some sail across the screen.

This simulator handles grids from 10 × 10 up to 1000 × 1000 cells, closed or wrapped edges, speeds from 1 to 60 generations per second, a library of famous patterns and RLE, the plain-text format enthusiasts use to share what they find.

How to use it

1. Pick "Draw" and click or drag a finger over the grid to bring cells to life. "Eraser" removes them, "Move" pans the view. The mouse wheel or a two-finger pinch zooms, and "Fit grid" shows everything again.
2. For a quick start, set "Random density" and press "Random fill". At 25 %, roughly one cell in four starts alive.
3. Under "Patterns", click a name, then click the grid to drop it. "Rotate 90°" (or the R key) turns it before you place it; Escape goes back to drawing.
4. "Start" runs the simulation, and so does the space bar. "Step" moves one generation, "+10" and "+100" jump ahead. "Back to generation 0" restores the grid as it was before the first step.

The "Generation" and "Live cells" counters follow every step. Your grid and settings stay saved on this device for next time.

The B3/S23 rule

Every cell looks at its 8 neighbours. A dead cell with exactly 3 live neighbours is born. A live cell with 2 or 3 live neighbours survives. Any other live cell dies, of loneliness or overcrowding. That is written B3/S23: B for birth, S for survival. All cells update at the same moment.

The "Rule Bx/Sy" box takes other rules too. The list offers four:

• Classic (B3/S23): the original Game of Life.
• HighLife (B36/S23): one extra birth on 6 neighbours. The "Replicator" copies itself there: its 12 cells become 24 at generation 12.
• Seeds (B2/S): no cell survives, and a cell is born with exactly 2 neighbours, so almost anything explodes.
• Day & Night (B3678/S34678): live and dead areas behave symmetrically, which gives slowly rippling blobs.

For your own rule, type something like B36/S125 and press Enter. The older survival/birth notation, such as 23/3, works as well.

Famous patterns

With the gun, the counter reads 36 at the start, 41 at generation 30 and 46 at generation 60: five more cells for each glider, as long as no glider has reached an edge. Three small starters take a long time to settle. The R-pentomino (5 cells) becomes stable at generation 1103 with 116 cells, 6 of the resulting objects being gliders heading away; it needs a grid of at least 600 × 600 without wrapping, otherwise the debris hits the edges and the outcome changes. The Acorn (7 cells) only calms down at generation 5206, with 633 cells. Diehard (7 cells) vanishes completely at generation 130.

Why it is so fascinating

Nothing in the rule mentions movement, yet gliders travel, guns fire and patterns copy themselves. It is the best-known example of emergence: complex behaviour arising from very simple local interactions. It has even been shown that, with gliders and guns placed the right way, the Game of Life can carry out any calculation an ordinary computer can.

In the classroom

In lower secondary school, pupils can work out the next generation by hand on squared paper, then check their answer here with "Step". In upper secondary computer science it is a classic programming project: store the grid in a two-dimensional array, apply the rule, and compare the output with this tool, for example the period of 15 of the pentadecathlon. In maths, the glider gun gives an arithmetic sequence that grows by 5 every 30 generations.

Frequently asked questions

What does "Wrap edges (torus)" change?

When ticked, anything leaving on the right comes back on the left and anything leaving at the bottom comes back at the top, as on a doughnut. When unticked, everything beyond the edge counts as dead, so a glider that hits a corner turns into a block.

How do I load a pattern from another website?

Paste its RLE text into the box and press "Import RLE", or use "Open a file" for an .rle file. The pattern is centred on a cleared grid, enlarged if needed, and the rule from its header is applied.

How do I keep what I made?

"Export grid" writes the RLE of the live cells, ready to copy or to save with "Download .rle".

Why did the simulation pause by itself?

Nothing was changing any more from one generation to the next, or every cell had died. A blinker or a moving glider does not stop it.