Glorantha is a rich and diverse setting and people can make their own decisions about what to do with it. With RuneQuest you can run everything from domestic “clan hearth” activities to “edgy” horror scenarios. You can run games that are very much about playing around with unexpected ways the rule mechanics interact or can play the game where the rules are simply a framework. Or whatever else you want. I’ve got my own preferences for how to play and the published books reflect that, but there is no one true way to approach the setting and the rules – in the end, use what works for you and those you associate with.
RuneQuest is intended for a grown-up audience – it deals with mythology, realistic depictions of the consequences of violence, death, etc. Most importantly, it is “fantastic” in the sense of Neil Gaiman’s “Sandman” – as it includes both things of wonder and of nightmares. All is present there, just as all is present in everyone. Or as Greg used to say, the World is Made of Everything.
My job is to present to you the setting as beautifully as possible, something which our whole team at Chaosium has done brilliantly. What you do with it is up to you.
RQG is very much in the model of Cthulhu and Pendragon – the rules system is integrated with the setting. If you want the raw rules system, that’s called BRP and we have issued an open license for that.