I play on Sryth, Ikariam and tribalwars, which are all browser based games, Sryth comes pretty close to what you are describing, none of them use forum software (except for their community forums). The kind of functionality I think you are looking for is not handled well by vb.
Having said that, I run
www.myth-weavers.com, and vb is excellent for that, and it is heavily modded to support rpg, just not the kind of rpg you are talking about.