You play as a miner that digs for minerals, gems and metals.
You build elevators to reach the 1000+ meters to the bottom of the earth. You'll come across ice which takes a special pick axe to break through.
The most important item (besides axe or drill) is your lantern which is the only way you can see underground. You can also upgrade the lantern to show you more of an area for digging.
It's dangerous to dig in the dark as it's really easy to fall down a shaft. i've spent 15 plus minutes filling up on over 100 gems just to fall down a shaft or die from a cave in. Which you lose everything youve found if you die. It can be extremely frustrating, and that's the only major problem i have with the game. You can die very easily if not paying attention.
The deeper you dig, the more money the diggable loot can become. Money that is used to buy and upgrade all of the items. From pick axes, drills (with different size gas tanks), a grappling hook that can extend to roof, elevators and ladders (which will be a best friend once you dig deeper) and bigger bags that hold more gems and items.
There are quite a few different styles of items and is a reason to keep playing.
There's only one piece of earth you dig in. This can take you hours and hours and even after about 35 hours, I have yet to see most of what's underground just because the area is so huge.
The graphics and style of the game are extremely simple seeing as how they just used the XBL Indie developers kit. There are nice extra touches like the trees swaying. The graphics don't take away from the gameplay and they designed everything well enough that you can tell what each item in the ground is.
This game is really great and i recommend it wholeheartedly. i think it was made by 2 brothers and is so then they did a great job making a simple concept into a game that can take you longer to beat than a lot of modern day RPG's.
Awesome game. And a great way to relax.