Very early screenshot, would be happy to accept any feedback.
On display here is the basic engine which loads a level from an array and uses a total of 80 actives for the 3D effect (4 actives per building). Uses "voxel 3D" tech from an example by Shab (http://www.castles-of-britain.com/voxelgraphics.mfa) as well as an infinite tile scrolling concept (no fastloops!) by AssaultAndy/Netninja (link forgotten). It supports infinitely large levels and is optimised to work smoothly even on iPhone 3GS.
I'm keeping the gameplay details under wraps at the moment but more info to come!