Octagon by Fred Saberhagen PB 1st Baen

This book is in VERY GOOD condition.

Players scattered across the continent are engaged in a game. Each player has certain attributes, including skill, strength, courage, cunning, and daring. Each has his kingdom. Each can ally with or attack any of the others ... But one player seems to have confused the reality of the game with the reality of the world: a player with the attributes of machine-like precision and mechanical ruthlessness. His name is Octagon, and he's out for blood. Even though he doesn't have any.