Doom

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.

Typical movement includes (double) jumping and crouching. Many objects can be climbed and by jumping it is possible to hang from ledges and climb up quickly. After acquiring the Praetor Suit early on, many types of upgrades are unlocked gradually by collecting tokens. Suit upgrade categories include environmental resistance, area-scanning technology (also affecting the 3D automap), equipment system, power-up effectiveness, and dexterity. Weapons such as the plasma gun, shotgun, heavy assault rifle, rocket launcher, lightning gun etc. can be upgraded with different points also earned during combat. In addition floating combat support drones can be used to modify weapons, often adding secondary firing modes. Next to the regular selection all weapons can be accessed directly through a weapon wheel while time is slowed down. There is another upgrade system where power surges, found in locations, are used to permanently upgrade the maximum amount of health, armour and ammo. In a codex entries on monsters, weapons, artifacts and environments are stored. Many monsters typical for the series return in an updated form.

Level usually consists of multiple objectives with markers that point in the right direction. Many levels are very wide with multiple approaches and the typical coloured keycards are used to lock off sections. Next to weapons, ammo and armor, levels contain secrets, optional challenges for rewards, collectibles, health stations and data logs. An entirely new feature for the series is the glory kill system. Killing enemies provides a small amount of health, but larger amounts can be acquired through glory kills. When enemies receive a certain amount of damage they stagger with a blue highlight. When close enough they turn orange and a dynamic glory kill finisher can be performed, different based on the angle. These glory kills can often be used to chain attacks together. Melee attacks are also possible as well as using explosive items in the environment. The chainsaw weapon has a specific use. It requires fuel and does a lot of damage, with fuel consumption based on the strength of the enemy. A chainsaw kill is rewarded with additional ammo for the regular weapons. Through optional rune trials in levels a large number of runes can be earned that can be equipped in a small amount of slots.

Multiplayer game modes include team deathmatch (kill enemy players in teams), soul harvest (defeated enemies leave behind souls that can be harvested), domination, warpath (control moving zones), freeze tag and clan arena. Multiplayer has a global experience system providing hack modules and aesthetic customization as rewards. These modules provide perks such as timers, boosts of the ability to see through walls. There are loadouts based on classes such as assault, sniper and ambusher. Custom loadouts can also be unlocked and defined. Some game modes allow characters to pick up a pentagram and temporarily become a demon who floats in the air, has a lot of health and deals a lot of damage.