modeling terrain is a pretty big pain in the ass. very arguous, but maybe that's because i'm doing it by hand instead of importing/generating a heightmap. ah well. currently it took me like... 2, 3 days to make 1 chunk of map? that doesn't sound too bad, and granted, it probably isn't, but also consider that this chunk is quite simple compared to others. well, it will be, when the others are made, which they aren't.

anyways, i'm getting off track. the hardest part of the terrain modeling process was actually getting the engine to work with it. yes, the terrain takes a lot of time, but it's more brain-melting than agony-inducing.
regardless, the engine is 3D in name only, and quite frankly, lacks a lot of features you want to actually do 3d in it.

for example: ground. we all know ground and how it's solid, and when you stand on it, you don't fall through.
Of course, to the engine, this is a different story. The engine only supports convex collision shapes, and if you don't know what that means, it basically means modeling terrain isn't possible.
now granted, there's probably a way to make it work by subdividing the terrain mesh, but doing that would be very difficult, and probably run like shit.
to cut a long story short, someone had made a script which scanned the geometry into a heightmap to be exported into a data table. I then took this script, then modified it to work better with a format that would be more useful for me. The end result is very much a "duct tape and superglue" solution, but it does ostensibly work.

how it works is that i export the terrain mesh as usual, and the engine displays it as such. then, i run a script to generate the heightmap, which i then import into the engine during initialization, which allows the engine to read the terrain height. from this, a very simple physics model is applied to the ground with the sole goal of keeping you on the surface.
what's nice about this is that i can still run the proper physics simulation concurrently with this simple model, which allows me to add in props you can run into without worrying about dealing with the heightmap for those, since such props will be far more geometrically simple, and something i can feasibly hand-model.