Is Triad Solved? What Perfect Play Looks Like

Yes — Sim is a solved game. With perfect play the second player always wins, forcing the first player to complete a triangle. Computer search verified this, and Mead, Rosa and Huang published an explicit second-player winning strategy back in 1974. Because almost no human plays perfectly, the game stays genuinely competitive.

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. If you are new to it, start with what is Sim.

What “Solved” Means

A game is solved when its outcome under perfect play is known with certainty — whether the first player wins, the second player wins, or perfect play draws. Solving a game does not require memorising every position; it means the theoretical result, and a strategy that guarantees it, have been established. For Sim the answer is settled: second player wins.

Who Wins Sim With Perfect Play

The second player. The reason a result even exists is that Sim can never end in a draw — a one-colour triangle is unavoidable, which is pure Ramsey theory — so every position is ultimately a forced win for one side. Computer search and the 1974 proof by Mead, Rosa and Huang both land on the same conclusion: with flawless play, the player who moves second can always make their opponent draw the losing triangle.

Solved in 1974 — but a Human-Playable Strategy Took Until 2020

Here is the twist that makes Sim more interesting than a typical solved game. The 1974 winning strategy is correct but intricate, far too complex to carry in your head during a real game. An explicit winning strategy simple enough for human players to actually follow was only found in 2020, by Wrzos-Kamińska (“A simpler winning strategy for Sim,” arXiv:2001.04024). So Sim was solved on paper for nearly half a century before anyone had a strategy a person could realistically execute.

Other Solved Games

“Solved” hides a lot of variety — the interesting part is often who wins, not just when it was solved. Sim stands out as a second-player win, which is rarer than you might expect:

Connect Four rewards the player who moves first; Checkers, fully solved in 2007, is a draw between perfect players; Sim flips the usual advantage and hands the win to the second player.

Why a Solved Game Can Still Be Deep

Knowing a solution exists is not the same as being able to execute it. Solved games can still demand complex decisions, careful reading, and real nerve — chess endgames are solved and people still study them. In Sim the objective is inverted, so positions are genuinely hard to evaluate: a move that looks safe can poison your options several turns later. Practical skill is the gap between theory and play, and that is where the game lives. To build that skill, read how to win at Triad — then play Triad free and test it.