Sprague-Grundy theory of games

The Sprague-Grundy theory of games is a theory of certain classes of games called impartial games, developed by R. P. Sprague[?] and P. M. Grundy[?]. It was originally developed for the game of nim.

It has been developed further by E. R. Berlekamp[?], John Horton Conway and others, and these developments are presented in the books Winning Ways for your Mathematical Plays and On Numbers and Games.