So what makes this game so fun?

[Wolftrap]

As a FPS and RPG gamer, this game would normally not appeal to me. But I cruise many forums and this game ALWAYS seems to come up! I've played games kind of like this (and I've read the features, etc.) and they fell flat on their face as far as interest. But many people tell me to try it because it's "so fun."

Okay, so I'm downloading the demo right now, but what is it about this game - that's NOT listed as an obvious feature - that makes it fun for YOU?