Are we setting this on Earth?

• Yes, though an unspecified number of years in the future. Enough time for the nuclear fuel cell powering the submarine to be on its last legs. Some of the sea life will have evolved into new an unfamiliar forms (Let’s just pretend a nuclear fuel cell and evolution proceed on similar timescales.)

What kind of submarine are we in?

• The submarine is a fictional deep-sea repair vessel sent down to perform maintenance on the well of an oil rig. For this reason the ship possesses a number of components for interacting with the exterior including a robot arm and ROV docking bay.

Why are we alone?

• You have woken from a medically-induced coma an unknown number of years in the future due to a near fatal injury suffered on the job.
• The original crew of the vessel is all missing. They evacuated following an attack to the vessel but were unable to recover you in your state.
• The duration of your sleep is indicated somewhat by the ship being visibly rusted from time and lack of maintenance.

Why are we (initially) stuck underwater?

• The ship’s most vital systems have managed to continue to run unmanned for all that time. These automated systems have been attempting to return the ship interior to a hospitable state for this entire period, only now having succeeded, you are awoken from your coma.
• The ship’s nuclear reactor only has enough fuel to power the bare minimum systems at the lowest settings. You must fuel the biofuel backup generators in order to continue.
• Once the ship is able to move its clear that the ballast in entirely inoperable, trapping you at depth as the submarine’s hydroplanes cannot compensate for your lack of buoyancy.
• You must find some method of increasing your ship’s buoyancy from deep underwater.

Why can’t we surface?

• The submarine’s internal temperature gets inconspicuously higher as you attempt to surface. If you get too close, you will overheat.
• Radiation increases when extremely close to the surface, indicated by a monitor on the vessel.
• Initial indications of your exploration would lead you to believe this in some way related to evidence of a war breaking while you were comatose.
• The reality is instead that the Earth’s magnetosphere has failed, motivating the conditions of scarcity and mass death that led to the aforementioned war.
• The only remaining habitable places on Earth are underwater.

What Is The Central Mystery?