How to read the grades
Progression grades compare bottlenecks on one account: a shut gate, a weak pickaxe, or cash spent on miners you will replace. Character grades use only public session numbers and say so. A higher letter is not a developer rank.
S tier
Player decision Do this first whenever the next layer is locked. Read the live nodes, buy that path, and keep cash for the fee and the new pickaxe.
Player decision Buy the tier your current zone shop stocks and press Equip Best. Do not save endgame materials that this game does not use; stock is a small shop cap.
A tier
Player decision Max the short utility tracks on the miner you will keep, then stack Damage Level until the next level costs more than the gate.
Player decision Roll miners who will still be in the crew after the next zone. Skip commons you are about to bench.
B tier
Player decision Take these once rocks break reliably and the next gate is not waiting on a required node.
D tier
Player decision Use them only until a stronger miner is on the plot. Then stop spending on them.