DOOM is a reboot of the first-person shooter series and it consists of three parts, accessed and loaded separately from the main menu: a single-player campaign, multiplayer with different game modes, and the SnapMap editor where custom maps and game modes can be created and shared. While many elements of the series are revisited, the focus for this entry is on fast gameplay based on movement, fights switching between different weapon combinations, and violent gameplay with brutal finishers, more akin to the first games. Compared to DOOM³ the areas are wider with more focus on verticality and rewarding an offensive approach, doing away with the slower horror aspect based on scares.The single-player campaign consists of thirteen levels. It is set on Mars on a research facility of Union Aerospace Corporation (UAC). The facility has been able to solve an energy crisis on Earth by channeling energy from Hell into a renewable power source called Argent energy. The flow is controlled through the construction of an Argent Tower, both harnessing the energy and providing a portal directly to Hell. When the player's character, referred to as the Doom Marine, wakes up in a sarcophagus-like prison, a full invasion from Hell is already in progress. The initial goal is to push back the invasion with the assistance of UAC research chief Samuel Hayden. Later on the focus shifts to stopping Olivia Pierce who heads a cult that wants to use the energy of the Argent Tower to bring all demonic armies through the portal. The game takes place in the research facility and in Hell.