Ragnarok Arena is a fan created mod for the Half Life engine released in October of 2006. The mod revolves around the tried and true concept of Multiplayer TCP/IP deathmatch in a side-scrolling environment.
The main idea behind Ragnarok Arena is to get the highest score by the end of a round. This is accomplished by killing other players with various weapon pick ups spread across the playing fields. What differs this mod from most released in recent years is how it's played.
However, the game itself ships with many furry player models, including an Arctic fox and the personal player model of the creator of the mod. This gave the mod the image of "Catering to furries", with a few sites attaching themselves to this idea. Even with this in mind, the mod itself ships with quite a few player models that have nothing to do with the concept of furries at all. In fact, most pay homage to priorly released mods in the Half Life Community.