One of the items on my role-playing to-do list is a Pendragon-style campaign using the Prince Valiant rules supplemented with Pendragon rules as needed.
Consider the times the historical Arthur lived. A time of chaos and confusion, when things were breaking down, and those perfidious orcs/saxons threatened to overrun everything and make every one their slaves.
Welsh myth combined with British legend and French romance. And in Christian symobology and you've got a keeper.
All in all grim and gritty fits the Arthurian trope. More Sir Gawain and his pre-Christian like than Lancelot and that crowd. But mad, manic, and doomed is a good feel for an Arthurian campaign.