Based on Game of Life: Kill the Sun

Conditions are the same:

Below is an initial state for Conway's Game of Life with a single pulsar. Living cells are white.

enter image description here

The area marked with red is your base. You are free to modify any of the red cells, but only those, and only in the initial generation. You are not allowed to do anything once the simulation starts.

Your goal is to move the pulsar so that its center is within area of the base – in other words, the game must reach a generation where only a pulsar with its center in the red area remains/loops infinitely and everything else is destroyed. Yet in other, way cooler words:

You have to construct a rocket to move the Sun and nothing else that was created in the process to remain.

The grid is infinite in every direction, i. e. runaway gliders still count as living.

EDIT: Because all answers are correct and there is no easy way to choose which one is the most valid, I'm picking the one with the most votes. I hope this will not discourage others to post other interesting solutions.

  • $\begingroup$ Do you have a solution to this? I'm inclined, at first glance, to think that it might not have one... $\endgroup$
    – user20
    Commented Apr 21, 2016 at 19:36
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    $\begingroup$ @Emrakul: This probably is solvable, because the pre-pulsar should be a fairly simple pattern to generate. I have not actually attempted to solve this yet, though. $\endgroup$ Commented Apr 21, 2016 at 19:38
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    $\begingroup$ @Emrakul Yes, and if there is no solutions after several days I will post mine. Also if solutions differ then mine. $\endgroup$
    – kamenf
    Commented Apr 21, 2016 at 19:44
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    $\begingroup$ its center (twice). please? $\endgroup$
    – Federico
    Commented Apr 22, 2016 at 8:53

5 Answers 5


6 cells, 111 generations

I found 12 unique (up to reflection) 6-cell solutions:

enter image description here

They all work by the same method as my previous 8-cell solution, forming a house one cell below the top of the base area at generation 6. Here's an animation:

enter image description here

There are no solutions with fewer than 6 cells (that stabilize within 200 generations).

previous solution: 8 cells, 111 generations

enter image description here

  • 1
    $\begingroup$ Awesome answer! Did you have a special method by which you created so many different solutions? Did you do them all by hand? $\endgroup$
    – minseong
    Commented Apr 22, 2016 at 6:20
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    $\begingroup$ @theonlygusti I did them by having the computer test a subset of all possible initial conditions, after finding a sufficiently small set of initial conditions. $\endgroup$ Commented Apr 22, 2016 at 6:47
  • $\begingroup$ @2012rcampion Wow! 6 cells... You will discourage others to try finding other solutions ;) $\endgroup$
    – kamenf
    Commented Apr 22, 2016 at 14:29
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    $\begingroup$ Is cell golf a thing now? Do we need a new SE for this? $\endgroup$
    – jpmc26
    Commented Apr 22, 2016 at 22:26
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    $\begingroup$ @2012rcampion Would be worth asking on our (PPCG's) meta, but I'm pretty sure that both this and the previous question would have been on-topic challenges provided some winning criterion was chosen (fewest generations or fewest live cells, I guess). $\endgroup$ Commented Apr 23, 2016 at 16:23

I have a solution:


I shamelessly stole the upper part from BaSzAt's 8-cell sun destroyer, and, by trial and error, found a 7-cell lower part that generates a new pulsar without interfering with the upper half. Like BaSzAt's solution, it takes 44 steps to gobble up the old sun, although the new one is already fully formed after 32 generations. The center of the new pulsar is located just barely within the starting area, at the middle cell of the bottom row.

Here's an animation of it:


In fact, the upper and lower parts of the pattern never really interact at all — they're just barely far enough apart to avoid interfering with each other. They do, however, "quasi-interact", in the sense that, on some time steps, there's only a single cell layer separating them. It just happens that, even though those cells have neighbors from both parts of the pattern, that never ends up making a difference as to whether they live or die in the next generation.

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    $\begingroup$ You didn't move the sun, you built your own and destroyed the original. It's kind of like the Sun of Theseus ;) $\endgroup$ Commented Apr 21, 2016 at 21:16
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    $\begingroup$ @WorldSEnder I assume that was a pun for Theseus' son, but I can't quite put my finger on it. Do you refer to Euripides' tragedy Hippolytus or Seneca's Phaedra? I'd love to enlighten myself. :) $\endgroup$
    – Oliphaunt
    Commented Apr 22, 2016 at 12:12
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    $\begingroup$ @Oliphaunt it's a pun to the ship of Theseus $\endgroup$ Commented Apr 22, 2016 at 12:15

19 cells, 41 generations, another humorous answer

EDIT: Only just noticed my answer to the previous challenge was logged in under the guest name user21465.

Continuing in the vein of humorous answers, here's another one. I thought it was going to be difficult and when I tried it I said ...

OH - blue

Here's the animation

Pulsar - OH - blue

  • 1
    $\begingroup$ Sorry to bother, but could you possibly change the colors of the red dots in the green field? You have accidentally hit upon a color combination that is almost unreadable to other people with partial red/green color blindness. (Like me.) $\endgroup$
    – zrajm
    Commented Apr 24, 2016 at 11:30
  • $\begingroup$ Oops! Should have remembered Ishihara tests from my earlier health and safety work. Colours are changed now. $\endgroup$
    – Ruutsa
    Commented Apr 24, 2016 at 22:43
  • $\begingroup$ Fantastic! Much better! Many thanx for the effort. $\endgroup$
    – zrajm
    Commented Apr 25, 2016 at 14:43
  • $\begingroup$ I think this is the best from multiple aspects: smaller number of generations and aesthetic of initial state =D $\endgroup$
    – justhalf
    Commented Apr 26, 2016 at 16:26

21 cells, 111 generations, last humorous answer

As they can be weary, this is my last humorous answer to this question. Moving stars seems to be a no brainer ...

No brainer

Here's the animation

Pulsar - no brainer


Posting my first solution, as I promised (69 generations):

enter image description here


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