Deep is an exploration game based on digging. While digging games exist - and I refer to famous examples such as Mr Driller, Dig-Dug and the various incarnations of Boulder Dash - they mostly rely on action. In these games, you get a cartoonish side-view depiction of the land you're digging and the gameplay tends to focus on frantically clearing dirt to reach diamonds or enemies or just to find the way down as quickly as possible.
Deep is slightly more RPG-based. Your goal is to scan the undeveloped area around your city for interesting signals and then purchase that area so you can dig it up. As you make money from your discoveries, you are able to upgrade your equipment in order to detect new and interesting things which will result in even more cash and you progress through the game in this manner.
Brief background to the game: The year is somewhere in the 8000s AD (though there's no-one alive who can remember the old date system). Humanity has managed to develop itself up to an advanced age where faster than light speed is possible. However, each time this is accomplished, a mysterious disaster resembling an earthquake packed with electromagnetic energy destroys all the technological advancements and drags humanity back into a pre-industrial age. Anyone who survives the earthquake wakes up to find no trace of their achievements and humanity has to rebuild from the ground up. Nobody is actually aware of this, but this event has occurred four times in humanity's past.
It is now a time period analogous to the 1940s (though without the war speeding things along). Humanity has been slowly recovering from the last Event and is only a few decades away from once again approaching the first steps into space exploration. You happen to be a Digger: someone who makes their living by using metal-detection equipment to scour the now-empty lands for materials you can sell to the developing cities. Because of the unique nature of this world, the ground is filled with remnants of several thousand years of technology, now inactive debris. Because these past generations of humanity at the peak of their advancement has all but stripped the natural resources of valuable metals and minerals of the planet, the only way to recover these necessary materials is by digging them up in "wealth zones" (actually the decaying remains of highly advanced cities). You live right on top of one of these.
Your detection equipment is limited to metallic elements close to the surface and so you must dig up the various near-surface scrap materials in order to raise money. You don't need to purchase land for this early segment as it's simply a tutorial about how you detect items and then dig them up. Eventually, you'll come across an actual find (which will be sent back to the nearby city for analysis) which will fund the next part of the game.
With the advanced detection equipment that your friends will research and create for you, you can start finding even bigger pieces of scrap metal to sell to interested parties. You'll start finding intact traces of the old civilisations too, which you can sell as cultural oddities. The game will eventually lead to clearing huge amounts of the Earth to recover entrances to whole buildings which you can then explore in a team and recover anything of use before destroying the entire building with concussion mines and selling the whole thing for valuable scrap. You'll also slowly start solving the mystery of where all this ancient stuff came from and why humanity seems fated to repeat its technological advancement over and over.
Gameplay-wise, the game will be split into three modes, the last of which won't be available until late in the game. The first mode is a digging simulator where you start digging at the most interesting places (you'll be dealing with several hundred feet of square land, so there's plenty to find). Anything dug up will be sent to your associates in the city to analyze for metallic components by your assistant on-site, which basically means anything dug up (including the ground soil) will be automatically be sent away for analysis. You'll start with a simple shovel initially, making progress slow, but you'll be able to upgrade digging equipment (as well as other things) as you progress.
For the second mode of the game you assume the role of your associates in the city, who are part trading company and part scholar research team. They actually receive discoveries from all Diggers in the areas surrounding the city and reward them for their findings, but since you'll soon outshine them (due to fortunate circumstances on your part) the company will end up being yours later in the game. To begin with, all you'll have available is a list of menu options to process the materials from your Digger protagonist. They will also clean up and preserve any intact items you will find. Both the metallic-compound search (in the soil you've dug up) and item clean-up are optional minigames you can play, though both can also be processed automatically without needing your control.
When the game gets to the point where you can start exploring whole subterranean buildings and outposts, you'll be assuming the lead of an exploration team and carefully exploring the dilapidated underground ruins for anything salvageable. There'll be various traps, both intentional (such as still-functioning security equipment) and incidental (such as doors that automatically open and shut at random). This exploration system will work in an FPS mode to properly recreate the feel of exploring the age-old ruin. It may also use a Metroid Prime-esque scanning system so you can continue to use your progressively-updated scanning technology underground. Your team is comprised of the protagonist Digger (who you will assume the first-person POV of) as well as several members of the research team in the city. Like the Digging mode, this mode will become more complex as you continually upgrade your tools using the discoveries you find.
I'm hoping to make this game an engaging mystery story going on as well as a highly playable sci-fi-esque treasure hunt. The storyline I have in mind doesn't simply involve aliens who zap us whenever we get close to reaching our potential: the story goes much deeper than that, with secret revelations and twists aplenty. Which is what one should expect from a game with a name like this.
