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Solving a Childhood Mystery: How BASIC Games Learned to Win (sublevelgames.github.io)

73 points by greentec ↗ HN
Hello HN!

As a teenager, I had this BASIC Computer Games book with a game called HEXAPAWN. Lines 900-970 were just cryptic numbers that made no sense to me. Finally figured it out decades later.

Turns out it's machine learning from the 1970s! The AI learns by literally deleting bad moves from an array. After losing ~10 games, it becomes unbeatable. Just 19 board states, no neural networks, no fancy algorithms.

Martin Gardner (who wrote about it) also mentioned MENACE - a tic-tac-toe learning machine made with matchboxes and beads. Same principle, physical implementation.

Made a JavaScript version if anyone wants to try. The AI really does get better.

15 comments

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michalpleban
So basically it has a table of all possible moves, and after losing a game, it deletes a move that led to the defeat? Then why not simply have a smaller table of moves right from the start, with losing moves already removed?
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Mountain_Skies
There was an article in 'The Rainbow' about the tic-tac-toe bead method of machine learning. For some reason, that particular method stuck in my head long after most other things I read in computer magazines of the time faded away. Maybe due to both the simplicity of tic-tac-toe and of the algorithm itself.
louthy
Ah, the memories of inputting listings from magazines and books like these, only to find that I’d have one character wrong and the whole thing would fail (and I didn’t know enough to fix it).

The vibe coding of its day! :D

lubujackson
I was a programmer a decade before my first Hello World!
ryoshu
Using Norton Utilities 1.0's hex editor to read and change save files for Moria :)
JLemay
The 1970s saw the birth of many foundational algorithms and concepts in machine learning, with research focusing on decision tree algorithms, clustering, and ensemble methods. I believe one of the first decision tree algorithms was created in 1973, crazy how early it all started!
aa-jv
In the 80's I apprenticed under a greybeard programmer who gave me all the shitty network code to write, while he experimented with neural networks instead of writing "old school" error correction logic for said network code.

I'm grateful for his bikeshedding, because it made me a network programmer and led to a fine career building Internet service providers, but I'll never forget his frustration .. "the computer is simply not big enough, we need to build a bigger computer" .. I wonder where he is these days. Hopefully retired.

diggernet
> As an aside, line 511 is entered when it fails to find matching values with the current game state for all 19 boards and flipped boards. It seems like it was originally intended to be a comment using the REM command like 511 REM REMEMBER THE TERMINATION OF THIS LOOP IS IMPOSSIBLE, but perhaps that part was omitted during editing, so it just starts with REMEMBER.

Actually, that line does start with "511 REM". There was no requirement for REM to be followed by a space.

reverendsteveii
this makes me want to rewrite the unbeatable tic tac toe algorithm I wrote back in high school so that instead of starting optimized it just walks through potential game states and eliminates them as it loses.