Start.
Give every normal user a full "mineral bag".
By paying a bag of minerals, the user can do a flat fee transfer once for free. The bag then become empty.
The minerals in the bag will evaporate after 24 hours if not used. The bag then become empty.
When the bag is empty, the user can start "mining".
4 hours after started mining, the bag will be full.
The user have to rest for 20 hours to be able to mine again.
Repeat.
Advanced users (annual subscriber):
Advanced users have 2 bags.
Advanced users can mine a bag of minerals in 2 hours.
Advanced users can mine again after rested for 10 hours.
Advanced users equipped special bags so minerals will evaporate only after 48 hours.
Elite users (lifetime member):
Elite users have 3 bags.
Elite users can mine a bag of minerals in 1 hour.
Elite users can mine again after rested for 5 hours.
Elite users equipped high-tech bags so minerals will evaporate after 72 hours.
Happy mining