I assumed that it was real, because it is xkcd. Now I tried it in https://playgameoflife.com/ and it works! It works because it is xkcd!

I can't find a simulator with a permalink. It would be nice if someone knows one, because copiying the initial pattern is very error prone.

There's one here: https://www.mixingmetaphors.dev/conways-game-of-life/

Thanks https://www.mixingmetaphors.dev/conways-game-of-life/?snap=o...

It would be nice to be able to select the size of the grid in that site. It was difficult to fit all the figure there.

Here is the RLE to reproduce the xkcd pattern in GOL implementations that support Run Length Encoded [1] (b=dead, o=alive, $=new line):

2b3o$2bobo$2bobo$3bo$ob3o$bobobo$3bo2bo$2bobo$2bobo!

In Twitch Plays Conway's Game Of Life [2] you can place Dr. Conway like so:

!rle 2b3o$2bobo$2bobo$3bo$ob3o$bobobo$3bo2bo$2bobo$2bobo! -4,-40

or use the shortcut command:

!xkcd -4,-40

Here is a short clip of what it looks like: https://www.twitch.tv/bzh314/clip/TardyGleamingQuailKeepo

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[1] http://www.conwaylife.com/wiki/Run_Length_Encoded

[2] https://www.twitch.tv/bzh314

Indeed it seems I was wrong. This is because as mentioned in another comment it is quite easy to create a self destructive pattern. Slider on top right is a common pattern. My bad, and impressive effort from xkcd !

i tried on an online simulator and it actually works!