Artifacts
This concept is part of game "Idle".
In it, on some maps, there are "Dig Site", and allowing the player to "Dig", with =W=.
Once started, it will disappear from inside-game, and will reappear in tab "Advancements - Permanent upgrades", which is outside-game.
Dig uses time, real time.
After dig done, there's "Artifacts". For example: name[Discount Hospital] rarity[Common] effect[Purchase a hospital upgrade at a 3% discount / Usable once every 24 hours] Upgrade[You can upgrade this artifact from Common to Uncommon by sacrificing four unequipped Common artifacts. The upgrade will take 12 hours. Artifacts have no effect while upgrading. Select the four you wish to sacrifice.]
An artifacts can be equipped/unequipped when in game. Maximum 3. CANNOT be unequipped when cooling down!
Can't equip 2 artifacts of the same type at the same time!
When a dig is in-progress, if another "Dig" is clicked, then: "Your excavation crew is currently busy at another dig site. Check their status on the Advancements tab in the lower right." - If game ended without dig site activated, it WILL be lost!