When you reach 100K depth you have the option to start a new game. You keep: artifacts, diamonds, & achievements. You lose: Gold, skills, & all upgrades.
You can choose to continue the game once you reach the core.
Should you do it?Edit
Yes. Not sure if at 1M depth, but yes.
After the reset I got:
- For the first level (only) ~250B gold. This might be a function of how far you get before reset (I got pretty far...), or happens always. If always, this is a very useful jump start, see the next point.
- Gaining in depth up still has a percentage chance of giving a chest or a diamond. The first depth levels are really easy, so you munch through a lot of them in a short time. I suggest the first build to be Archeologist ;) It's not a sea of items but a lot, especially when compared to how rare items are later in the game.
- A ton of togenium (2k for me). This must be a function of how deep I got, probably linear. Togenium can be used in a special shop to buy 10% "boosts" for any type of mustachio. These increase DPS, DPC, duration, and gold/sec(!). This boost percentage works like mustachio's individual bonuses do - it's a multiplier to the total. But individual bonuses do not ever change gold/sec! This makes boosting very, very useful! If that wasn't enough, the duration ceiling, normally 48h, can be exceeded by boosting!
Many say the game was broken September 2015. I say it was just made more difficult. It's not possible to get MechaZilla in a hundred years unless you do the core resets and use boosting.