ONE ™ Eclipse is a science fiction action game with adventure elements. This is a first-person shooter with a deep plot and an open world. The plot unfolds in 2035 when members of the «AVALON» rescue mission of the «A.M.B.R.A.C.» research company sent to Mars, in order to find out the mysterious reason for the disappearance of the first group of colonists and scientists. The protagonist of the game is Bryan O’Callahan - a young astronaut who wakes up on a ship after a long sleep in hibernation and realizes that the ship is completely empty, and the rest of the crew disappeared without a trace.