Thanks, the source for the terrain system is up here: https://github.com/chadams77/LunarOasis/blob/main/main.cpp#L802 (line 802-914). Basically the levels are stored as a 64x64 grids of numbers, which on level start is turned into a 512x512 height map by randomly applying depth sprites for various sizes of rocks such that empty parts of the grid are not filled, then a 64x64 window is rendered every frame and some basic lighting is calculated and the terrain is shaded. For destruction the heightmap is modified in real-time.