I created a new cave system for my game. After the normal world generation process the caves are cutted out of the material. Here is an entrance:
The caves are narrow on the surface and grow in size when you go deeper:
And of course you can find resources in them. Here you can see for example coal (and if you look precise you can also see iron ore in the image above):
+1 i want to see it in action
I plan to release it soon, but currently I have some issues in the game which must be resolved. So for example I want to be sure that the world data format can be used in the next release (so the player does not lose his world). That's not so easy as converting an old format into a new one is not possible because of the amount of data. In a 25 m^2 Landscape you have about 500 billion voxels. This means about 6 terabyte raw data (compressed it is much much smaller). So I must create a data format which is capable of using different file versions in the same file. That means implementing new features and see if a problem occurs.