Short answers, pulled from the story.
Ludus duodecim scriptorum translates as 'game of twelve markings.' The name refers to the twelve markings found in each of the three rows on most surviving boards, giving a total of thirty-six markings.
Ludus duodecim scriptorum was played by people from many walks of Roman life, including soldiers, nobles, and ordinary citizens. Boards cut into stone at public forums and bathhouses made the game accessible to anyone who passed by.
Each player used fifteen pieces and three cubic dice. Very little about the specific rules has survived, though a possible beginners' board with lettered spaces has suggested a particular path for piece movement.
Boards for Ludus duodecim scriptorum were carved into stone surfaces at public forums and bathhouses. An ancient example was also excavated at Kibyra, an archaeological site in southern Turkey.
Ludus duodecim scriptorum is thought to be the ancestor of tabula, a later Roman board game. Both tabula and modern backgammon belong to the same family of games, known as tables games.
The earliest known written mention of Ludus duodecim scriptorum appears in Ovid's Ars Amatoria, written between 1 BC and 8 AD.