3x3 is a first player win. All three possible starting moves win.
4x4 is a second player win. All three possible starting moves all lose for Black. The symmetrical replies win: 1. B1 2. D3, 1. A1, 2. D4, and 1. B2 2. C3 are all wins for White.
All six opening moves win, as first proven (as far as I know) by (She 2013) with brute-force search, taking over 1011 nodes for each search. See the NoGo publications page. In (Cazenave 2021), many rectangular boards are solved, with the largest being 5x5, solved in "46 092 056 485 moves". The SBHSolver of (Du 2023) is orders of magnitude more efficient, and was also used to show that Black can win in at most 21 moves, but not less. All rectangular board with up to 27 points were (re-)solved, including previously unknown results for 3x9, 1xn with n = 10..27, and 2xn with n = 10..13.
The CGTSolver described in (Du 2024) solved all NoGo boards up to 1x39 - twelve boards more than in (Du 2023).
Created: Nov 29, 2011 Last modified: Sep 5, 2025, Martin Müller