A little hint: 64-bit compatibility means that executable code, like DLLs or EXEs (not XML or LUA!), needs to be compiled for another target CPU, which is really no big deal. Sceneries are not executable code, just a huge amount of data, even the "code" for moving objects is just data from the CPU's point of view. So, a scenery for 64-bit is exactly the same as a scenery for 32-bit. If somebody says that their scenery is ready for 64-bit, all they're talking about is additional DLLs they use... mostly for copy protection.