You are Lieutenant Kenshin Herakles, of the Horizon. You wake up, alone, on the derelict remains of your vessel.
In "o2" you are on a limited supply of oxygen, and can consistently resupply your suit to avoid oxygen starvation. You can explore the remains of the Horizon to find out what happened to the ship and her crew.
"o2" is a narrative drive, first person experience with themes derived from classic cosmic horror and science fiction.