Excalibur
Geoffrey of Monmouth, in his "Historia Regum Britanniae" ("The History of the Kings of Britain", c. 1136), Latinised the name of Arthur's sword as "Caliburnus" (potentially influenced by the Medieval Latin spelling "calibs" of Classical Latin "chalybs", from Greek "chályps" ["χάλυψ"] "steel"). Most Celticists consider Geoffrey's "Caliburnus" to be derivative of a lost Old Welsh text in which "bwlch" (Old Welsh "bulc[h]") had not yet been lenited to "fwlch" (Middle Welsh "vwlch" or "uwlch"). In the late 15th/early 16th-century Middle Cornish play "Beunans Ke", Arthur's sword is called "Calesvol", which is etymologically an exact Middle Cornish cognate of the Welsh "Caledfwlch". It is unclear if the name was borrowed from the Welsh (if so, it must have been an early loan, for phonological reasons), or represents an early, pan-Brittonic traditional name for Arthur's sword.
Spirit of Excalibur
As the title suggests, the game is based on Arthurian legend. Both fictional and historical sources are used to recreate the atmosphere of the age of King Arthur and the Knights of the Round Table, and to draw out characters' names, history and relationships. The game's sources include medieval works such as Thomas Malory's "Le Morte d'Arthur", modern ones such as Marion Zimmer Bradley's "The Mists of Avalon", and a number of historical treatises on Arthur of the late 1980s. The game is set in the year 539, shortly after the Battle of Camlann at which King Arthur has been mortally wounded by the traitorous Mordred. Britain urgently needs a new king who can reunite its scattered realms and bring the Round Table back to its former glory. Arthur left a successor in the person of Lord Constantine the Crown Regent.