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  3. Conway's Game of Life
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Conway's Game of Life

Cellular automaton on a board up to 300 by 300, with RLE import and export, custom B/S rulestrings (HighLife, Seeds, Day and Night), pattern stamping, and pan and zoom.

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A sample round

You paste the Gosper glider gun from LifeWiki as RLE and run it, to see unbounded growth from a fixed pattern.

RLE pasted

#N Gosper glider gun
x = 36, y = 9, rule = B3/S23
24bo$22bobo$12b2o6b2o12b2o$11bo3bo4b2o12b2o$2o8bo5bo3b2o$
2o8bo3bob2o4bobo$10bo5bo7bo$11bo3bo$12b2o!
What Conway's Game of Life produces

After 120 generations

36 live cells at generation 0
68 live cells at generation 127
  the gun itself, plus five gliders travelling away diagonally
rule B3/S23 taken from the header

RLE is the interchange format LifeWiki publishes and every desktop Life program reads, so a pattern someone else designed loads exactly as intended, rule included. The gun is the classic proof that a finite pattern can grow forever: it returns to its own starting shape every 30 generations while emitting one glider each time, so the population rises without ever stabilising.

Watch Complexity Emerge from Simple Rules

Set up a pattern of living cells, press play, and watch it evolve. Conway's Game of Life is not a game you play but a simulation you watch: cells live, die and reproduce by three simple rules, and out of that come gliders, oscillators and guns. This version runs boards up to 300 by 300, reads and writes RLE (the format every desktop Life program and LifeWiki uses), takes any B/S rulestring so you can run HighLife or Seeds instead, and lets you stamp patterns onto an existing board rather than replacing it.

How to play

  1. 1Click or drag on the board to toggle cells, or press Random for a starting field at the density you choose.
  2. 2Load a pattern: click its name to centre it on a cleared board, or switch to the stamp tool to place it without clearing.
  3. 3Paste RLE from LifeWiki into the import box to load any published pattern, rule included.
  4. 4Change the rule if you want something other than Conway. B36/S23 is HighLife, B2/S is Seeds.
  5. 5Press play, or step one generation at a time with N. Undo with Ctrl or Cmd plus Z.

Tips & best practices

  • Try the R-pentomino: five cells that take over a thousand generations to settle down.
  • Use the stamp tool to aim a glider at a still life and see what the collision leaves behind.
  • Switch to Seeds (B2/S) on a nearly empty board. Nothing survives, so everything is pure propagation.
  • Turn edge wrapping on and a glider that leaves one side comes back on the other, which is how you keep spaceships in play on a small board.

Why play it

  • Learning about emergence

    See how complex global behaviour arises from local rules, then change the rule itself and watch a completely different universe appear.

  • Computer science education

    Cellular automata are foundational to computation and complexity. The Gosper gun, loaded straight from its published RLE, is a working demonstration of unbounded growth.

  • Working with published patterns

    Paste RLE from LifeWiki to study a specific pattern, or build something and export it for a desktop Life program.

  • Art and pattern exploration

    Stamp several patterns onto one board and watch them interact, which is where the interesting collisions come from.

Controls and rules

  • Boards from 10 by 10 up to 300 by 300, which is 90,000 cells
  • Under 2 ms per generation on a full 300 by 300 board, around 100 generations per second while drawing
  • RLE import and export, the format LifeWiki publishes and desktop Life programs read
  • Any B/S rulestring, with presets for HighLife, Seeds, Day and Night, Life without Death, Maze, and 34 Life
  • Stamp mode with a ghost preview, placing a pattern without clearing the board
  • Pan by dragging with the pan tool or by holding space, plus zoom
  • 26 built-in patterns across still lifes, oscillators, spaceships, guns and methuselahs
  • Adjustable random-fill density
  • 200 steps of undo, stored compactly rather than as full grid copies
  • Cells coloured by neighbour count, so crowding is visible before it resolves
  • Board remembered between visits, and share links that carry the whole board
  • Generation counter, population sparkline, and a generations-per-second readout
  • Optional edge wrapping, turning the board into a torus
  • PNG export of the current board

The Rules Behind the Magic

Each cell looks at its eight neighbours every generation. Under Conway's rule a live cell with two or three neighbours survives and anything else dies, while a dead cell with exactly three neighbours comes to life. That is the whole thing, and it is written B3/S23: born with 3, survives with 2 or 3. The rule field takes any B/S notation, so B36/S23 gives HighLife with its self-replicating pattern, B2/S gives Seeds where nothing ever survives, and B3/S012345678 gives Life without Death, where growth never reverses. Presets cover the well-known ones and an invalid rulestring is reported rather than silently ignored.

The engine works on a flat typed array and counts neighbours by scattering from live cells rather than testing every cell, so the cost tracks the population rather than the board area. Those counts are then used twice over, once to decide the next generation and once to colour the current one, instead of being computed separately for each. The board renders as a single image blit rather than tens of thousands of individual rectangle fills. Together that is what makes a 300 by 300 board practical: measured in the browser, a generation on 90,000 cells takes under 2 ms, and the simulation sustains around 100 generations per second while drawing.

RLE import and export is the feature that connects this to the rest of the Life world. Paste the Gosper glider gun from LifeWiki and it loads, rule and all; export what you have built and it opens in Golly. Patterns can also be stamped: choose the stamp tool, pick a pattern, and it is placed where you click with a ghost preview first, leaving everything already on the board intact. Clicking a pattern name without the stamp tool still centres it on a cleared board, which is the older behaviour kept as the quick route.

Smaller things that matter in use: undo keeps 200 steps as compact encodings rather than 200 full copies of the grid, pan works by dragging with the pan tool or by holding space, the board is remembered between visits, the share button copies a link with the whole board encoded in it, and pasting such a link while already on the page loads it rather than doing nothing. A generations-per-second readout and a population sparkline show what the simulation is actually doing.

Frequently asked questions

Is this actually a game?

Not in the traditional sense. It is a zero-player game: you set the initial state and observe. The interest is in designing the starting pattern, or in loading one someone else designed.

What is the largest board I can use?

300 by 300, which is 90,000 cells. That is practical rather than nominal: a generation takes under 2 ms and the simulation runs at roughly 100 generations per second while drawing.

Can I load patterns from LifeWiki?

Yes. Paste the RLE into the import box. The header is read for the bounding box and the rule, so a pattern that needs HighLife switches the rule for you. Export produces RLE that other Life programs read.

Can I run rules other than Conway?

Any B/S rulestring works. Presets cover HighLife (B36/S23), Seeds (B2/S), Day and Night (B3678/S34678), Life without Death (B3/S012345678), Maze (B3/S12345) and 34 Life (B34/S34). An unparseable rulestring is flagged and Conway is used until you fix it.

Do all patterns eventually stabilise?

Most do, settling into still lifes and oscillators. Some do not: a glider gun emits gliders forever, so its population grows without bound until the board edge stops it. Turn edge wrapping off to let a gun run cleanly.

Can I save my patterns?

Four ways. The board is remembered between visits automatically. The share button copies a link with the whole board encoded in it. RLE export gives you a portable text form. PNG export saves a picture.

How do I place a pattern without wiping the board?

Switch to the stamp tool, pick a pattern, and click where you want it. A ghost preview follows the cursor, and Escape cancels. Clicking a pattern name with the draw tool still clears and centres, which is the fast route when starting fresh.

Private by design

The game runs entirely in your browser. No account is needed and no gameplay data is collected.