Medieval literature included the Matter of Rome (classical mythology), the Matter of Britain (King Arthur), and the Matter of France (the Carolingian cycle).
The Matter of France is obviously what you want here. It focuses on Charlemagne and his paladins, most famously Roland. The most famous element of the Carolingian cycle is the Song of Roland. The source texts are the medieval chansons de geste, from the 11th and 12th centuries; later versions added in more magic and monsters, as is often the case. They later spread to Italy in the 14th, 15th, and 16th centuries and produced another set of epics--Orlando Furioso and Orlando Innamorato are the most famous, and are even more off-the-wall (at one point in Orlando Furioso his wits escape and he has to go to the moon to retrieve them). The Italian epics later influenced English literature like The Faerie Queene.
Keep in mind they're fighting Moors and Saracens (ie, Muslims), so while they are often portrayed as chivalrous opponents in the stories you might still find some things objectionable (as with any 1000-year-old source).
There's an RPG by Chaosium, Warriors of Charlemagne, that recently came out and might be of interest here. (Appropriately enough, it's modified from the Arthurian RPG Pendragon.)
You could also look at actual French RPGs like Cadwallon or Agone that have been translated.
