Ranks range from A-Free. At each rankup, you unlock a new mine and get a rankup key. At the free rank, you are able to venture out into our wilderness.
Once you get to free rank, you are able to prestige. Prestiging resets your ranks and grants you more powerful rewards as you go on. The current rewards for prestiging are:
Permanent 10% sell booster at every rank
Legendary crate key every 5th prestige
Prestige mine at the following intervals: