Seasons show the inflation of each token and season indexes are the multipliers for every sphere(OIL, GOLD, IRON).
There are 3 seasons indexes: oil index, gold index and iron index. These are values that exist in the range from 0.8 to 1.2.
The system recalculates indexes every hour. It takes into account the numbers of staked NFTs and active minings. If their proportions are different, it increases one index and decreases another.
For example, if the player starts mining with an Iron miner which gets 12 IRON as a basic reward and 1 IRON as season based reward. If the iron index at this time is 1.2, at the end of the mining player will claim 12 + 1 * 1.2 = 13.2 IRON.