You certainly need a CoF, though what that should be is lost on me.
I'm sort of envisioning something like
Ganondorf's reincarnated castle from
Ocarina of Time, although maybe not so much lava, but certainly something
like an edge of the world and a floating castle. Maybe a little Steampunk-y?
Also, you can do better than those tree models, most of them really don't look good,
and the dead pine model should be used more sparingly and cleverly, placed like they
are right now they're really not very good looking.
There's also much better barrel and crate models out there, hell you could even search
up better ones just by heading over to the resource section.