Chaturanga — "four limbs", the four divisions of an ancient Indian army — is the game from which chess, shogi and xiangqi all ultimately descend. No complete period rule text survives, so every modern implementation is a reconstruction; ours follows the widely used Murray reconstruction and says so plainly.
Variant implemented
Two-player reconstructed Chaturanga on 8×8: mantri (counsellor) moves one step diagonally, gaja (elephant) leaps exactly two diagonally, no castling, no double pawn step, promotion to mantri only. Bare-king is a win.
Board and pieces
8×8, 64 squares.
Setup
Back rank: ratha, ashva, gaja, mantri, raja, gaja, ashva, ratha. Eight padati in front.
Turn
Move one piece according to its type.
Capture and scoring
Move onto an enemy piece to take it. A padati captures only diagonally forward.
Win condition
Checkmate the raja, or capture every enemy piece except the raja — the "bare king" win.
Draw condition
No draw by agreement; the move limit ends a game that goes nowhere.
Special rules
The mantri moves one step diagonally. The gaja leaps exactly two squares diagonally, jumping whatever is between. There is no castling, no double pawn step and no en passant. A padati reaching the far rank promotes to mantri and nothing else. Stalemating your opponent is a loss for you — the stalemated player wins.
Computer opponent
Alpha-beta. The evaluation weights material, pawn advancement and central control.