About Triad

Triad is a free online version of Sim, the 1969 pencil-and-paper game by Gustavus Simmons where two players draw lines between six dots and the first to complete a triangle in their own colour loses.

The rules in brief

Two players take turns drawing a line between any two of six dots, each in their own colour.
You must avoid completing a triangle of three dots joined entirely in your own colour.
The first player to complete a same-colour triangle loses — and a draw is impossible.

Learn more

What is Sim?
How to win at Triad
The Ramsey theory
Is Triad solved?
Triad vs tic-tac-toe
All guides →

Invented as Sim in 1969 by Gustavus Simmons · K6: 6 dots, 15 edges · R(3,3) = 6 · solved: second player wins.