Ephemeral Tic-Tac-Toe

Ok, I was nerd sniped by the idea of Ephemeral Tic-Tac-Toe, where your moves fade away and disappear after four turns (see https://kottke.org/24/08/0045170-ephemeral-tic-tac-toe-eac), so I spent some time this morning implementing a computer player using my javascript MCTS framework.

Perfect play seems to result in an endless game. I am not perfect ;-)

You can play against it here: https://www.downtherathole.com/ephemeralttt/

h/t @kottke

Oh, interesting, I cut games off at 100 turns (declaring a draw) and ran some simulations.

At 10,000 search trails per move, between two evenly matched players, about 80% of games ended in a draw:

draw,mcts10000,mcts10000
79,20,1
0.79,0.20,0.01

At 100,000 search trials per move, the first player was able to force a win:

draw,mcts100000,mcts100000
0,100,0
0.00,1.00,0.00

So, maybe with perfect play this game is a first player win!

I should mention, if you’re interested in weird Tic-Tac-Toe variants, you might enjoy Notakto: X-only Tic-Tac-Toe played on multiple boards where the goal is to AVOID making three-in-a-row!

Thane Plambeck solved this game and we made iOS and Android apps that let you play against the computer. Links to the apps and Thane’s paper here: https://www.counterwavegames.com/notakto/

The apps are free to download and play (no ads).