I've been skimming over this topic, and I must say, the idea of the Castle leading to Diamondus seems like a good idea to me. In the final version though, for accuracy story, Diamondus'll need to be reached by Devan's time machine, and that area could become Carrotus, etc. Like a free roam type area, where bosses need to be beaten to reach the next area, and certain devices would allow you travel to certain areas. In short, something like a free range area sounds like what I mean, and I think it'd do some good...

Anyway Baggers, if you care, you could PM or IM me, since I'm relatively good with plot and stories, etc.