Armies

A fast Stratego engine, players that learn by playing themselves, and the research behind deciding well when most of the board is hidden.

Board
One byte per cell
Engine
Millions of moves a second
Rules
Tournament anti-chase rules
expectimax against greedy, a recorded game.start of 116 moves

The ladder

All results
  • ExpectimaxTop
    1535Elo
    343-7-110 in 460 games
  • Greedy
    1393Elo
    303-8-229 in 540 games
  • Rollout
    1283Elo
    19-0-81 in 100 games
  • Ataraxos smoke
    1090Elo
    18-26-36 in 80 games
  • Random
    1000Elo
    127-219-354 in 700 games
  • N-tuple leaf
    0Elo
    0-0-0 in 0 games

Games, wins, draws and losses over every registered game of September 18, 2026 (the 16-world depth-2 cell of the sweep counts for the expectimax rung) plus a 60-game random-expectimax pairing; Elo is a logistic fit over the pairwise effective scores with random anchored at 1000; rungs with zero games are unmeasured; built by scripts/build_second_pass_assets.py.

Hidden information

Each side sees only its own ranks. Play means acting on beliefs about forty face-down pieces and updating them as they move and fight.

Search at play time

The ladder climbs from greedy rules to expectimax over sampled worlds, then to networks trained by self-play and refined by search.

An engine you can measure

The rules run allocation-free on one byte per cell, so millions of positions a second feed the arena and the training loop.