Amazons

Goal of the game

Each side has four amazons on a 10 × 10 board. The player who can no longer move loses, so you must secure more room than your opponent.

How it works

• White goes first. A turn is played in two steps, with the same amazon.
• Move: the amazon moves like a queen in chess, as many squares as you like in a straight line or diagonally, without jumping over any amazon or arrow.
• Shot: from its new square, it shoots an arrow, also like a queen. The square it lands on is burned for the rest of the game. The arrow may pass over the square the amazon has just left.
• There are no captures. Little by little, the arrows carve the board into closed zones.

Controls

• Tap (or drag) an amazon, then its destination square; then tap the square the arrow should hit.
• Before shooting, tap the amazon again to cancel its move.
• The "Territories" button colours the squares each side can reach first.

About the AI

The evaluation is inspired by the work of Jens Lieberum: for each empty square, the AI computes in how many queen moves and king moves each side can reach it, deduces the territories and how solid they are depending on the phase of the game, then penalises amazons with little mobility. The alpha-beta search is selective: at the root, all moves (more than 2,000 at the start) are evaluated; deeper down, the best moves are preselected before their shots are examined. Master level searches for about five seconds per move.