This implements the old school voxel landscape (as seen in games like Comanche) in GameMaker Studio 2 as described below. You can also get nice sample maps from this site.
http://simulationcorner.net/index.php?page=comanche
You will need YYC to make use of this....
Can use freely in games, and source can be given away freely. Source/project can not be sold or re-uploaded.
End User Licence Agreement (EULA).