I have found a nice game on the-underdogs: Celtic Tales: Balor of Evil Eye
http://www.the-underdogs.org/game.php?id=185 (and there is a manual also)
For many parts it reminds me KoDP (founding a tribe, emmissaries,
tributd, cattle raid....) on a pure irish background (who says that
Dragon Pass Tribe are in fact irish ? ) with traditionnal heroes, myths
gods and many more.
I haven't play a lot but seems fun.