Sanga by tamaki.
"The River inside the Mountain" made me think of 'In the Hall of the Mountain King' (part of 'Peer Gynt' by Grieg). Then I thought: 'Dwarves like more angular construction that is underground'.
Gnomes in roleplaying games and some myths are more likely to live on the surface. If so, then this is a perfect home for them. It is earthy in both shape and substance.
This would be a good model for someone experimenting in 3D because of the simple, yet powerful, shapes.