Random Move Chess aka Infinite Monkey Chess

Two monkeys sit across from each other at a chess table. Both make completely random yet legal moves for eternity. Who wins? How often?

MP_1076668

First, here is an example game run with these rules looks like:

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After running approximately 500 games here is the resulting ending:

untitled2

Interestingly, the first-move advantage still holds in this absurd variant. My initial guess of games that would end in checkmate was approximately 2%… nowhere near the actual 26%. The fact that stalemates are significantly lower than checkmates also is a bit curious. I am sure there is lots of room here for chess theory but I have no real desire to touch that.

Notes on the implementation

  • Castling / Au Passant-ing is possible and occurred
  • Pawns randomly select which piece to be promoted to (which makes the games really funny to watch)
  • Draw by repetition occurs after 200 moves without a piece being captured
  • Each game takes ~1.5 minutes on my school laptop

This was created using a fork of ChessPeace created by Zachary Danziger in Matlab. There is no way I would be able to scratch the surface of this problem without his work: so many thanks to him. I’d upload the code but its 98% his. The little work I did was to increase the draw by repetition threshold, trim unnecessary code, cut down on fprintfs, induce looping and an overall scoring system.

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One thought on “Random Move Chess aka Infinite Monkey Chess

  1. Pingback: Infinite Monkey Chess Part II | Barron Wasteland

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