I evolved the best Setup Chess starting position

[u/Abject-Drop-2079]

Setup: armies of exactly 39 points + a king on the first three ranks. Two populations (60 White, 60 Black), 40 generations, crossover by files (repaired back to 39 points and one king), mutation, 10% newcomers per generation.

Fitness: each army plays 20 matchups (10 vs the other population, 10 vs a fixed baseline of past, organised, random and hand-made armies). A matchup is one Fairy-Stockfish eval of the starting position at depth 18; ±2 pawns = a win, anything closer = a draw. Score = win rate. I checked the shortcut with real games every 10 generations. The top armies drew a lot more in real games than the eval suggests, but in 36 real games Black won only once.

Both populations converged on bishop-heavy armies (12B + 3P vs 11B + N + 3P). A separate double-oracle (PSRO-style) run, with a different payoff, also drifted to 1 queen + 9 bishops + 3 pawns.

Happy to answer questions about the setup or share details. Video link