That was pretty fun at first but the late (?) game gets pretty frustrating.
Having coffee only affect the lowest miners is bad enough when aiming for the emerald cave, but even moreso when artifact hunting. Having to sit through a dig, potentially burn (and re-buy) coffee, then reset to have another go gets tedious fast!
edit: okay, coffee isn't necessary for artifact farming if I disable the Spawn upgrade, but this still feels like a pretty grindy loop for unknown reward!
edit2: the reward was nice, game was still fun overall, but the artifacts could definitely do with being less RNG-dependent.