GURPS Middle Ages I Second Edition, softback supplement for GURPS, by Graeme Davis
“Welcome to the age of chivalry, fealty, and piety. GURPS Middle Ages 1 takes you to the rich, dark world of medieval England, where knights fight for King and God, nobles trade favours and treachery, and peasants work the land.
Three major periods are covered: the Saxon Kingdoms, Norman England, and the High Middle Ages. Medieval combat is described at length, from simple jousts to the deadly Crusades, with details on melee weapons, siege weapons, armour, and castle defences. Also included are magic, religion, and beasts both real and mythical . . . plus maps of castles, an abbey, and medieval England and France.”