I noticed that this mod lacks a picture, so I generated this using the headless --generate-map-preview option: http://fs.marvin.nuke24.net/uri-res/raw/urn:bitprint:AZXA2O4XBLQYXPPL35KANTX32FFP4GHO.TRC2SA5ENIHQZ2ATOHAEAK6RQJH2VIEOSRBLZFY/h-tree.map-preview.png (which took 5 minutes).
This mod is abuses the terrain generation system in an interesting way. It was not designed for this type of fractal (the entire thing is computed for each tile, hence the slowness), but you sorta made it work, and the Lua code to do it is surprisingly straightforward.
