Blindfold 9x9 challenge

Not many know but there exist an old bot “cosumi”. And this bot has a blindfold option:

So here’s a challenge: beat all 5 AI levels of cosumi blindfolded on 9x9 (there’re bigger boards but higher AI levels are disabled there). It’s definitely possible because cosumi is not very strong. Important point: if you play on top of a stone at any moment, you automatically lose.

Here’s my wins against all levels (there were also like ~50 losses, but those doesn’t count, ok):

At the end of the game you can replay it and below the board it displays text of sgf record, so you can copy-paste it into empty file, change extension to sgf and upload to ogs library, for example.

So yeah, go and play it, post games, discuss. And don’t forget that go is all about suffering and hitting your head against a wall.

Here’s chipped stone to make post prettier:


I didn’t get the meaning of “blindfolded” until I actually tried to play a game. :smiley:

I see! :smiley:

I’m not ready yet for this challenge. :slight_smile:

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Thankyou for posting this @S_Alexander. First attempt, fail. :frowning:
Thanks to you I am back at the ‘recognising atari’ stage. :roll_eyes:
Will definitely try again. Maybe when I don’t have a headache.
Link added to profile page.

Probably worth mentioning that the big green ‘Start’ buttons are for ads. Just click on the board size you want to begin.

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There is also one-color go on Kosumi, which you may find much easier (I do at least), but still very interesting :smiley:


“Your color is black”… then only white stones… :smiley:

I think “hitting your head against a wall” suits perfectly. :smiley:

I’m still stuck with questions like “is this 20-stones group of mine alive yet or do I need another move?” :joy:

(((actually, I’d like to be able to remember a game for reviewing it afterwards, but for now I recall only about 20 moves or so… need training… I will, someday…)))


Ok, I confess: I had to try at least one-color.
After 26 moves I was completely confused (though it was a very simple situation).
Here is my attempt to atari a group of 3 stones on the left border. :joy:


I was very surprised when, two moves later, those stones didn’t disappear! :rofl:

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Yes, I know that feeling :smiley: when you place the final stone feeling victorious, awaiting tasty prisoners and empty space on the board…

… and then nothing happens…

and the emptyness you were expecting at the board starts crawling into your heart instead…


It’s also possible to play one-colour go here on OGS, though you must take it on good faith that your opponent is doing the same (if that’s what you agreed to)

In the top right menu where you pick the look of your board and stones, the two stones on the far left can be set to any colour. Setting them both to the same colour results in one-colour go :slight_smile:


One color go is relatively easy even for SDK (after a bit of practice). It may very well be that it’s easier on 19x19 because of joseki and more normal moves, while in 9x9 it’s all fighting and any move is valid. Plus, cosumi is pretty peaceful on 19x19. If you want to play on ogs, I’m up for a game.

Blindfold on the other hand is very hard. Here’s pros playing blindfolded (literally, heh) until move 100, with 1 chance to look at the board; if a player can’t continue, they can take blindfold off but receive penalty 5p/move until 100 moves:

Credit to Hayang on lifein19x19 for finding this video and explaining the rules.


Victory at last. Against level 1 :v:

BlindGoCosumiLvl1.sgf (359 Bytes)

I find this incredibly hard. I have to basically memorise the game so I can keep track of what’s where. I can’t for the life of me, just visualise the board and play normally.

My question is this. Is it possible to learn visualisation with practise or is it simply an ability that you either have or not?

If it can be learned and improved with practise then I imagine that playing Blind Go would also improve my reading ability in normal live games.

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I believe that it’d be superhuman to memorize the game without understanding it. Thanks to your knowledge yuou are able to replay bits of the game in your head knowing why certain things happened.

The deeper the understanding of reasons, the simpler is game recovery. It’s exactly the same as with replaying games from memory on 19x19. If your understanding is deep enough you are able to reason the game back to life.

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Victory at last ! Blind-9x9-Lvl5Cosumi

In case link fails

PB[COSUMI(Level 5)]

Just a snapshot:

I’ve been trying to do this in a more complicated game with at least three (total) groups but I suppose l must be content with first blood being a “your side, my side” kind of game.


This is hard. My best attempt ended when I wanted to place a stone where I already had one. But I was playing black and behind on the board anyway.

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