The difference between making an engine that specifically runs in a 2D plane and an engine that is free 3D is pretty huge. When you have free 3d, you suddenly got to have a much more complex map/object handling system which puts far more strain on both server and client. Not to mention the map editor and format itself becomes far more complex. You can no longer use a simple grid system. I would heavily suggest staying in a 2d plane, engine wise, for the first release as it would very much increase the chances of this project actually reaching its end goal (taking on too much is one big reason for failed hobby projects). There are already game engines for free 3D-flight. Let those engines focus on what they do and instead let this project become the pinnacle of top-down combat. This isn't a small thing like the friction debate which is pretty silly considering the easy of implementing it. This is a huge part of how the engine will work. Very little can be done game engine wise until the issue has been clearly decided.
