8 days! Super fun game. I think a 7-day is possible, but it would require a lot of luck on early days (especially day 1, need two miners days 1).
Strategy:
- Re-roll until the first three days are +worker, +worker, +energy.
- Priority is upgrades, but rock is limiting early on. Don't save resources if you can buy a useful upgrade or another worker.
- +speed upgrade is useless for trying to minimize days.
- Coffee is very powerful. Coffee is probably worth it if you can get to copper and more than pays for itself if you can get to silver. ALSO: coffee can be bought and used at the end of a round - never buy coffee in advance.
- Because deeper metals are so much more expensive than earlier metals, all that matters is getting to deeper levels. Therefore, chance for 2x resources and more minerals spawned is not worth it (more minerals actually slows down progress). Clover can be worth it if you have extra cash lying around.
- Day 5: silver
- Day 6: gold
- Day 7: platinum -> max workers and get as much energy + strength as possible.
- Day 8: I got to the emerald cave without even using coffee that day (barely).