Not sure what your prefs are, but I have to recommend fasti because we have an Arthur from the 2004 film and my guess is that they would like to have a Lancelot.

Fasti takes place in Ancient Rome. The gods have chosen people to come and fight in a war against the Titans. There are monthly events and a lot of room for player plots and participation in the setting. The game ad is here so that can give you more information about it. I'm also happy to try to answer any questions.