The first painted version of The Empty Mine (the map in the previous chapter) was judged "coming along, but still not ideal". The problem was clear once it was put beside the games it wants to resemble: I had pushed most of the map into impassable mountain and forest, rectangular fills with corridors carved through them, on flat olive grass.
The reference maps are mostly open ground. Rock is ridges and outcrops that make chokepoints, not wall-to-wall plateau. Every rock mass sits inside a band of brown dirt; dirt also forms worn paths and yards. Grass is saturated green with soft mottling. And the main structural tool is not mountains at all: it is trees you can cut down, which make lanes and walls that change shape as the mission goes on.
The rule that became an engine bug
"Choppable forest is a must-have" sounds like a content note. It turned into an engine finding: harvesting a forest tile crashed the game, because the tileset only had solid tiles and the engine's wood-clearing code expects a lookup table for mixed edges. That lane reverted the feature and reported the trace. An engine step a few days later guarded the wood-clearing path properly, and wood now comes from forest tiles you can cut.
Terrain look v2
On September 21 the new look was approved from engine captures, and the decision was to rebuild The Empty Mine on it first: green mottled grass, dirt with a fringe, boulder rock ringed by dirt, water with shallows and sand, individual tree units over a choppable forest floor, feathered building yards, and a ground layer baked per map.
The composition rules were written down at the same time so every later map follows them: forest as the base's walls, unfenced harvest faces, walls only across approaches, a node-and-path layout, and pathing checked across the whole map.