#GhostRoboArmy for life!. Set in a UAC facility on Mars, the player, implicitly a space Marine, awakens to find himself chained to a table of otherworldly origin in a UAC lab. After breaking loose from his chains and dispatching nearby zombies, he acquires the Praetor Suit - a powerful set of armor which enhances his abilities. He then sets out to discover what has happened in the facility, fighting his way through undead and demons in the process. An intelligent robot named Samuel Hayden remotely gives him access to VEGA, the facility's artificial intelligence. Samuel and VEGA explain that a portal to Hell has been opened on the base. Since this portal was opened, the tens of thousands of UAC employees on-base have either been turned into zombies or killed by demons released by an antagonist, Olivia Pierce. Up until this point, the base was being used for research into harnessing the power/energy of Hell to foster technological advancement. The Marine is then told they will need to deal with Ms Pierce "in time" but is first tasked with securing the base from certain destruction. Gameplay. Single-player. Doom's single-player mode was described as having "badass demons, big effing guns, and moving really fast" as key principles, according to id Software executive producer Marty Stratton. The game will feature a large arsenal of weapons, which can be collected and freely switched by players throughout the game. Weapons such as the super shotgun and BFG 9000 will return. Additionally, melee weapons such as the chainsaw, which can cut enemies in half, are also featured. Many enemies from the original games like the Revenant, Mancubus, and Cyberdemon return as well, some redesigned. As the combat system of the game puts emphasis on momentum and speed, the game allows players to perform movements like sprinting and double-jumping. A combat system known as "push forward combat" is featured, which discourages players from taking cover behind obstacles or resting to regain health. Players instead collect health and armour pick-ups scattered throughout levels, or kill enemies to regain health. A new mechanic introduced in Doom is the melee execution system, similar to that of the popular PWAD Brutal Doom. When enough damage has been dealt to an enemy, the game will highlight it, and allow the player to perform a melee takedown. id Software states that Doom's campaign will be more than 13 hours long and the "Ultra-Nightmare" difficulty level will have permadeath. Multiplayer. The game's multiplayer is being developed in conjunction with Certain Affinity. Several multiplayer modes, such as traditional four-player deathmatch and team ("clan") arena, as well as domination, warpath, and freeze tag. Players can also use power-ups and teleporters in a multiplayer match. Players can pick-up a pentagram, one of the powerups featured, to transform into and fight as one of the demons featured in the game. The game will also include a built-in tool titled "Doom SnapMap" which allows players to construct custom maps, create new game modes and share them with the online community. At launch, the game features 9 maps..