nx_folkgame_race_lib.nx

nx_folkgame_race_lib.nx -- THE RACE FAMILY: a track, a randomiser, entry, bearing off, hitting and blocking. SCOPE STATED BEFORE ANY CLAIM. Twenty-two registry rows are race games. This engine covers the TRACK sub-family -- a linear course both players run in opposite directions: Backgammon, Nard, the Royal Game of Ur, Senet, Sugoroku, Liubo, Zohn Ahl, Main Kabul. The cross-and-circle boards (Pachisi, Chaupar, Ashta Chamma, Ludo, Yut Nori, Patolli, Pancha Keliya) fold four arms onto a per-player track and are a SEPARATE rung; the spiral and ladder boards (the Game of the Goose, Hyena Chase, Mehen, Snakes and Ladders) need special-square rules and are a THIRD. Saying which eight of the twenty-two this reaches is the difference between a family row and a family claim. STATE ENCODING: state[c] is a SIGNED count -- positive is the first player, negative the second. That is the representation the game itself has, and it makes a point's owner and its height one number instead of two that can disagree. DIRECTION: the first player runs from index 0 toward the end and bears off past track-1; the second runs the other way and bears off past 0. So a point's PIP VALUE differs per player, which is why fgr_pip takes a side rather than reading one number off the board. THE RANDOMISER IS SEEDED AND LIVES IN THE SAVED POSITION. A race is not deterministic, but a REPLAY of one must be: the seed is scalar slot 12, inside what fg_save and fg_load copy, so restoring a position restores the die that follows it. A seed kept beside the position instead of inside it is a seed a save silently loses, and the replay then diverges from the game it claims to be replaying. license_tier: ORIGINAL No hw writes (Rule 26).