Add tool materials better than steel

[CasimirKaPazi]

At the moment when you found enough steel you are pretty much done with progression.

Instead there should be several additional stages to have various levels which get harder to obtain. Some might be so hard that you can loose the ability to get them and have to work your way back.
The different levels should also behave differently. Not just, dig deeper and get better materials.

Also make iron spawn deeper, and make copper more common.

Ideas:

• Tin (no tools) and Bronze (better than copper, worse than steel)
• Carbonate steel (or iron versus steel) similar to pixture.
• More industrialized tools, or different handles which adds more use times.

[CasimirKaPazi]

0805685

[CasimirKaPazi]

See discussion MTG#2093