Subterranean Survivability

Subterranean Survivability is a Minecraft mod (addon) focusing on the further development of underground spaces, particularly making them more friendly to live in, and more interesting to explore. The mod is in it's very, very early stages, and much more content is planned. It currently stands as a proof-of-concept. 

Key Ideas: 

Exploration is not only further developed, but also encouraged. Certain crafting paths are locked by biome discovery. Staying on your toes is wise. 

Included are various variants of ore tiers. For example, Pyrite is equivalent to wood, as is Tanzanite. The difference being, they can be found underground.

Notes:

As stated previously, this mod is in very, very early stages of development. This development, however, is very transparent. To view it's progress, one may like to join the mod's Discord Server.