Minetest Mod for adding caves with rails and wood constructions similar to Minecraft.
Screenshots and information: https://forum.minetest.net/viewtopic.php?f=9&t=10225
License is WTFPL. You just do what the fuck you want to.
You can install this mod by putting the directory "RailCorridors" into the "mods" subfolder of your minetest folder. Maybe it is needed to convert into lower case: "railcorridors"