I heard Ragnarok has two versions. One is from Korea...
That would be the mawha (Korean manga) by Myung-Jin Lee. Which, BTW is an excellent read! I'm not very familiar with the game, but the logos appear to be the same as the manwha! I am no curious to see how much they're related.
(http://home.earthlink.net/~saucer/iris.jpg)
and the other one is from Japan which was entitled as the Mystical Detective Loki Ragnarok. The only thing they have in common is that both of them contains stories about NORSE GODS.
There is indeed an anime with that title. And, like the manwha, it is based on Norse mythology. I'm not really familiar with Mystical Detective Loki Ragnarok. But you can download the 26 episode series pack (http://animesuki.rut.org/series.php/136.html) from AnimeSuki. ^_^