Doom: Mercury Rising

The Doom: Mercury Rising campaign is a 100% Fan-made project. The story's creator and developer is a single person, whose username is TheMercurian. The campaign is set in 2141, therefore it is a prequel of Doom 3 and Doom (2016). It is built using the SnapMap editor feature available in the Doom (2016) game.

The Mercury Rising project is currently under development. It will contain 33 maps in total, and the focus is presently on completing the first chapter, Mercury Rising - Part One (consisting of 10 maps), as well as reworking and testing the maps completed so far.

Background[]

The basic idea for the Doom: Mercury Rising campaign first arose in September 2019, during and after a second playthrough of the Doom (2016) game.

"I loved the visuals of D2016. There was no need to abstract anything. The levels were so detailed that I truly felt like I was on Mars. During my second playthrough, I consciously looked for areas where I could linger and immerse myself in how the developers had envisioned a UAC facility on an alien planet. Let me show you a few examples:"

It was at this point the question first arose: "Why should travel from Hell only be possible to and from Mars?" Why couldn't travel to other planets be possible? The release of Doom Eternal only reinforced this concept.

"Man, I was hugely disappointed with Eternal. I barely finished three levels of the first game. I kept whining that I wanted D2016! Why wasn't Eternal like that, just with more combat and more new, detailed worlds? That's what I want, and I'm going to make it!"

The lack of immersion in the world of Doom Eternal greatly motivated the project. However, this also influenced the beginning of the story: the detailed and branched lore of Doom Eternal only appears in the story thread from the middle or one-third mark of the campaign. Until then, it builds upon and connects only to the creator's favorites: Doom 3 and Doom (2016).

"But when the campaign was already well underway, I played through Eternal twice. Getting over my initial bitterness, I was impressed by its level of detail, too. Not just the lore, but the levels themselves are very intricate. I was glad I didn't give up and played Eternal twice! It was hard to go back to D2016 afterward. But I'm also happy that I put it aside at the start, because it gave me a strong motivation to create my own campaign!"

The Doom: Mercury Rising campaign was originally intended to be a sequel to Doom 3, wedged somewhere between D3 and D2016 on the Shared timeline. However, since the four years between the events of the two games are already somewhat crowded due to the D3 expansions, it couldn't be easily inserted. Thus, the decision was made that the campaign would be a prequel, set in 2141, preceding the events of both games. This time choice also provided additional creative freedom, as all characters from the aforementioned games are still alive.

Development[]

The development of the Doom: Mercury Rising campaign began around January 2024. The roughly five years preceding that were dedicated to gathering campaign ideas, continuously modifying the campaign story, and studying Mercury's locations.

The development environment was also uncertain for a long time. However, since the locations themselves—industrial environments on alien worlds, the depths of Hell, and the characters involved in the story (e.g., Betruger, Hayden, Vega, and even the demons) are fundamentally part of the Doom universe—the SnapMap editor naturally became the chosen environment, with all its advantages and limitations.

As of the current development status (and likely until the full completion of the first chapter, Mercury Rising - Part One), a further limiting factor is that the development itself is taking place within the NVIDIA GeForce NOW cloud gaming service. This means the available building blocks, props (and their logical connections) in the development environment are those supported by "vanilla" SnapMap, supplemented by elements or solutions copied from useful "asset" maps created by enthusiastic community members of the SnapMap Discord server.

Therefore, for example, the possibilities offered by the SnapHak editor tool are NOT available with the current cloud gaming service. Should the development of the first chapter be completed, the current SnapMap development environment may be expanded (Gamer PC + SnapHak) or switched entirely (DOOM Eternal: idStudio).

Historical Overview of Development, Current Status, and Ongoing Work
Date	Milestone	Map	Length / type of work
Jan 2024	Project started	-	-
19th Feb 2024	Release	Rudaki Power Station (FIRST CONTACT)	1 mo. / dev
23rd Apr 2024	Release	The Solar Railway (THE HEAT)	2 mos. / dev
26th Jun 2024	Release	Thakur Cross Service Station (ARRIVAL)	2 mos. / dev
20 Jul 2024	Release	Lu Hsun Gates (UNINVITED)	1 mo / dev
		Memory optimisation	0.5 mo. / rework
20th Sept 2024	Release	Haystack Canteena (WHAT HAPPENS IN VEGAS)	1.5 mos. / dev
		Searching for new solutions	0.5 mo. / research
		Memory optimisation of the last two maps	1.5 mos. / rework
9th Jan 2025	Release	Catullus Steelworks (THE FURNACE)	2 mos. / dev
		Further memory optimisation practices	1.5 mos. / rework
31st May 2025	Release	Jobim (Halfway Station) (SUBMERGED IN IRON I)	2.5 mos. / dev
		Campaign lore review	0.5 mo. / lore
15th Jul 2025	Pre-release	Jobim (Shaft) (SUBMERGED IN IRON II) beta	1 mo. / dev
		Memory optimisation of ALL maps	1 mo. / rework
Today		Finalising the campaign lore and level designs	1.5 mos. / rework
Today		Creation of Fandom Wiki pages	0.5 mo. / wiki

From the table above, it is clear that developing a more complex map requires 2 to 2.5 months. However, as the campaign progresses, an increasing amount of time is consumed by finding new memory optimization solutions and tricks, implementing them across already completed maps, and dedicating the freed-up memory to useful purposes (e.g., further improving the visual design of that particular map).

Furthermore, it is becoming increasingly evident that there is a distinct difference between a map being in a 'tested and playable-ready' state and a 'truly finished' state. This difference (which includes the final design of the map, its characters, their messages, dialogue, the campaign's lore specific to that map, and the creation of the corresponding wiki page) adds significant time to the project beyond the core development period.

Due to these considerations, the decision was made that:

The development of the entire Doom: Mercury Rising campaign must be divided into three main parts, creating three chapters aligned with significant narrative shifts, such as leaving a specific region, returning from Hell, etc. Thus, the campaign will be divided into three chapters: Part One, Part Two, and Part Three.
The second conclusion is that, keeping quality in mind (meaning not rushing the remaining maps of Part One and delivering them in a 'truly-finished' state) it will likely take at least another year to fully complete it, even in the best-case scenario.
The third decision, since a one-year timeframe is too distant, is that the first chapter will be deployed in three stages, consisting of 3x3 map packages. (Plus the secret map at the end.) This brings the 'truly finished' release and deployment of the first three maps (THE HEAT, ARRIVAL, and FIRST CONTACT) within accessible reach, potentially happening this year.

Gameplay[]

In terms of gameplay, the Doom: Mercury Rising campaign closely resembles Doom (2016), given that the campaign itself (at least the 10 maps of the first chapter in its current state) is available and playable within SnapMap, which is part of the 2016 game. The gameplay is much faster than its predecessor, Doom 3, and perhaps slightly less aggressive than what is experienced in Doom Eternal.

Due to this strong resemblance, it is easier to review what the Mercury Rising experience does NOT contain, both because of SnapMap's limitations and the rethinking of the 2016 campaign.

No Automap. The SnapMap framework itself is the fundamental constraint for this feature. Although the levels are essentially built from modules, the system does not automatically generate a map for the level. Manually implementing this would be incredibly resource-intensive.
No Weapon Upgrades (as typically seen in the 2016 campaign). In the original campaign, weapon mods could be acquired from Field Drones, and the weapons could then be upgraded by obtaining and spending upgrade points. In the Doom: Mercury Rising campaign, upgrading weapons from one state to a higher state is neither possible nor necessary. This is because, as the campaign progresses, weapons are acquired with pre-set mods (Standard or Mastered), or without mods early in the campaign. Accordingly, the role of the drones has also changed. Detailed information on this change is available in the Collectibles section.
No Preator Suit Upgrades (as typically seen in the 2016 campaign). In the original game, the Preator Suit was upgradable using Preator Tokens scattered and collected throughout the levels. In the Doom: Mercury Rising campaign, the tokens collected from the red soldiers serve a different primary purpose. More information is available in the Collectibles section. Despite this, the player does gain abilities during the campaign, but these are acquired in a pre-determined, "mandatory step-by-step" order as the campaign progresses.
No Rune System. Since the campaign development has not reached the point in the story where Runes would be required, the omission of the Rune system is not yet set in stone. However, its potential appearance in gameplay is only expected in the Mercury Rising - Part Two chapter.
Difficulty settings: for the Doom: Mercury Rising campaign, one thing is certain: The campaign itself does NOT feature any functionality that allows for difficulty level adjustments modifiable by the SnapMap editor's capabilities. There is no such function, neither at the campaign level, nor at the map level, nor in a way that can be dynamically adjusted during gameplay. The Doom (2016) game does include a built-in difficulty setting, but its actual effect on the game is not definitively clear. According to answers provided by Google Search, which is powered by modern artificial intelligence, it does affect gameplay. In contrast, the community members of the SnapMap Discord server suggest that it does not really have an impact.

The following features ARE included, which the 2016 campaign did not contain:

Demon Rune – Players can pick up a Demon Rune and transform into a demon. On specific maps, you can transform into one of three pre-defined demons: Revenant, Mancubus, or Baron of Hell. More information is available in the Collectibles section.

Collectibles[]

From the initial concept and throughout the development of the Doom: Mercury Rising campaign, great emphasis has been placed on ensuring that the campaign's own plot, the characters' backstories, and other information belonging to the Doom universe are communicated to the player with sufficient detail. Thus, some form of communication with the player became unavoidable. The SnapMap feature set offers approximately three options for this purpose: one is text messages displayed on the screen (MESSAGE), the second is a message simulating voice and text transmission (TRANSMISSION MESSAGE), and the third is a longer block of text appearing in a message window (DATAPAD MESSAGE).

In cases where the communication of a distant (not physically present) character needs to be simulated, the TRANSMISSION MESSAGE is used in the campaign. In situations where the player is involved in communication with present characters, the traditional MESSAGE function is utilized, as if the action were subtitled or narrated on the screen. However, the DATAPAD MESSAGE is used most frequently in the campaign, typically in situations where a story needs to be told, requiring a large amount of information to be conveyed in a single window. This is because using the DATAPAD MESSAGE is the most optimal approach regarding the quantity of the message transmitted versus memory requirements.

Due to the frequent use of DATAPAD MESSAGES, the function and operation of the collectibles familiar from the Doom (2016) campaign have been slightly modified and tailored to the needs of this prequel campaign. The following shows how:

PDAs:
Yes, PDAs... It is well known that the use of PDAs was mainly characteristic of Doom 3 and was not followed by Doom (2016), much to the delight of many players. In the Mercury Rising project, due to the aforementioned goal (to convey the campaign lore) and the limited possibilities of SnapMap, PDAs are again taking the main role! Naturally, considering those players who are not interested, picking up the PDAs and viewing the messages is optional, not mandatory, and does not influence the gameplay. (The number of instances where collecting an item is mandatory in the Doom: Mercury Rising campaign is very small. In those rare cases, the item is marked as a POI, or Point Of Interest.) Returning to PDAs, they are typically used in the campaign when they contain communication from a specific person (UAC PERSONNEL).
Books:
They function very similarly to PDAs (picking them up opens message windows), but they typically contain information related to the given map or Mercury (ENVIRONMENTS).
Dossiers:
Their operation is similar to the previous two cases; information regarding military operations can be extracted from them (UAC OPERATIONS).
Preator Tokens:
The function of the tokens differs from what was customary in the 2016 campaign. As described in the Gameplay section, they are not needed for weapon upgrades, so in the Mercury Rising project, they hide information related to military operations (UAC OPERATIONS).
Minifigures:
The function of the figures also differs from what was seen in 2016. In the Doom: Mercury Rising campaign, characters are categorized into 3 groups based on their importance: minor characters, 'moderately important' but noteworthy characters, and finally, 'important' or main characters. All communication between any character (at any level) occurs via PDA or Dossier. However, the minifigures hide additional background information about the 'moderately important' and 'important' characters when the player picks up that character's minifigure. These figures are usually hidden; picking them up is accompanied by the well-known sound effect and also counts as +1 secret found.
Field Drones:
Field Drones are not frequently encountered in the Doom: Mercury Rising campaign. In the current state of development (and according to the current concept), these drones are messengers, delivering messages or very rarely, packages, whose sender is the campaign creator, TheMercurian himself (or perhaps a fictional company he creates in the future).
Demon Runes:
As described in the Gameplay section, Demon Runes transform the player into a demon. The manner and duration of this transformation vary per map, depending on the current needs of the campaign story. Generally, this transformation is never an end in itself; it is always consciously planned, suggested, or sometimes even necessary to proceed through the level. This transformation may also be accompanied by a displayed message, which is then worth reading and taking seriously.
Others:
The Doom: Mercury Rising campaign contains countless other collectible items, which can be the most varied of things (Teapot, Wrench, etc...). Picking up such collectible items is usually optional, serves some secondary purpose (not essential for completing the level), and does not result in a message display.

Weapons / Equipment[]

The weapon arsenal of the Doom: Mercury Rising campaign is very similar to Doom (2016) game. The number of collectible weapons has a theoretical upper limit (a maximum of 15), but this limit is not practically felt, as the player typically possesses a maximum of 10 weapons during gameplay—fewer at the start of the campaign and increasingly more as it progresses.

The weapon distribution is also similar to the basic distribution of the 2016 game. Additionally, in the Mercury Rising project, weapon acquisition is styled more like a campaign rather than a multiplayer game. Weapons do not float in space; they typically lie on the ground or a table, or lean against something. This can make them slightly harder to notice, although they are highlighted from the environment with a blinking green light or other effects. This campaign-style weapon handling is further reinforced by the fact that when the player picks up a new weapon, the old one is not discarded; the new one is simply added to the arsenal in the appropriate slot. Furthermore, if the player already possesses a weapon of that type and the new one is a more advanced version, the old weapon is lost, and the new one becomes available in its place with maximum ammo. For example, upon picking up a Shotgun with Standard Explosive Shot Mod, the old shotgun is lost, and the new one takes its place with maximum ammo.

The following list details the weapons that will be available in the Doom: Mercury Rising campaign. The list begins with the weapons for the first chapter, followed by the planned weapons and equipment for the remainder of the campaign:

Mercury Rising - Part One

EMG Mark V pistol
Chainsaw
Combat Shotgun, later Standard Charged Burst and Standard Explosive Shot modded shotguns are available
Heavy Assault Rifle, later Standard Tactical Scope and Standard Micro Missile modded assault rifles are available
Rocket Launcher, later rocket launcher with Remote Detonation mod is available
Super Shotgun
Vortex Rifle
Frag Grenade

Mercury Rising - Part Two

Burst Rifle
Plasma Gun, later plasma guns with Stun Bomb, or Static Field mods are also available
Hellshot
Grenade Launcher
Chaingun, later Gatling Rotator modded chaingun is available
Shield Wall

Mercury Rising - Part Three

Static Rifle
Lightning Gun
Gauss Cannon, later gauss cannon with Precision Bolt mod is also available
BFG9000
Personal Teleporter

Regarding Health and Armor, and Power-ups, the Doom: Mercury Rising campaign is consistent with the Doom (2016) game, and the same collectible items are available.

Enemies[]

The monster set for the Doom: Mercury Rising campaign is also similar to the monsters in the 2016 game. The reason for this is that the SnapMap level editor only allows a subset of the monsters seen in the campaign to be placed on a map; only the so-called "standard demons" are placable, while bosses, such as a Cyberdemon, are NOT.

However, the editor does provide the option to customize these standard monsters individually, ultimately allowing for the creation of "boss-fight-like" gameplay experiences by "supercharging" creatures that are already at a sufficiently high base level. In the first chapter of the campaign (the first 10 maps), the player may encounter the following enemies:

Monsters of Mercury Rising - Part One:

The monsters for the remaining maps of the campaign are still under wraps. One reason for this is whether there will be a change in the development environment during the creation of Mercury Rising - Part Two and Part Three, i.e., whether options such as the DOOM Eternal: idStudio will become available.

If there is NO change and development remains based on SnapMap, the increasingly frequent boss fights on the maps may be supplemented with logic seen in Doom Eternal. For example:

Buff Totems: When a Buff Totem is near, all Demons in the area are toughened up, stronger, and meaner than ever.
Possessed Demons: Monsters that are possessed by a Spirit, making them much stronger than their traditional versions. Once the demon is defeated, the possessing spirit must be killed within a set time.
Cursed Demons: Monsters that, if they get close to the player, possess the player himself (inflicting a curse).

Plot[]

The largest corporation on Earth, the Union Aerospace Corporation (UAC), due to profit-driven economic, legal, and moral reasons, had long since expanded beyond Earth's borders by the 22nd century and begun outsourcing its research and development, terraforming, industrial, and economic activities to other planets in the solar system. Until now, the official Doom franchise has only mentioned Mars and Earth among these planets, even though the world physically reached and conquered by humanity harbors many other interesting locations and secrets.

The Doom: Mercury Rising campaign attempts to connect the dots and patch the holes between the detailed worlds presented in Doom 3, Doom (2016), and Doom Eternal. Every Doom fan knows this is a tough nut to crack, but the Mercury Rising project attempts to weave these parallel storylines together and resolve their mutually exclusive ("either-or") relationships.

"For a true Doom fan, there is no sweeter challenge."

The campaign will showcase a world where the UAC corporation has established a foothold in numerous parts of the solar system. It is present in the following locations:

Earth, of course. In theory, Earth houses the UAC company headquarters, the High Council, and from here, they direct the 'pieces on the solar system chessboard' (facilities, military operations). But, as they say: "nothing is as it seems".
Mars, naturally! The campaign demonstrates that the UAC is simultaneously present at multiple locations on Mars, creating the possibility for the co-existence of the Betruger and Hayden storylines. Additionally, there are UAC bases on Phobos and Deimos.
Mercury. The campaign reveals why Mercury became the very first planet to be conquered, despite Mars being the most optimal choice in the solar system for an extraterrestrial research and development facility. It explores how and why Mercury played a key role in the UAC's expansion.
Venus. For the duration of one map in the campaign, the Venusian cloud cities will be presented, floating along the planet's equator, submerged in the upper layers of Venus's dense atmosphere. The player gains insight into the daily lives of the UAC workers there and the mysteries of the raw material extraction operations carried out there.
Ceres and several larger celestial bodies in the asteroid belt.
Jupiter's 4 Galilean moons: Ganymede, Callisto, Europa, and Io.
And finally, Saturn's 2 moons, Titan and Tethys.

The campaign treats Hell as a kind of nexus, a gateway. It is an extra dimension that exists above or below (a matter of perspective) conventional spacetime, with multiple entry and exit points. It accepts the 'primacy' of Hell as presented in Doom Eternal—that it is the most ancient dimension—and demonstrates how different levels of the UAC view this problem/opportunity from different perspectives. Some simply see Hell as a militarily secure shortcut (to shorten travel between UAC stations in conventional spacetime). Others see the future in harnessing the energies found there (e.g., Hayden). A multitude of different viewpoints clash during the campaign's story, and in their own way, each is correct.

Returning to the plot of the Mercury Rising project, the whole campaign is mostly set on Mercury, in 2141, before the events of Doom 3 and Doom (2016). The campaign is divided into three chapters. Each chapter has its own Wiki page, the links to which are also included in the list in the Chapters and Levels section below. The LEVELS belonging to each chapter are also available on the respective Wiki page for that chapter. Similarly, the PLOT associated with each chapter can also be found on the chapter's own Wiki page.

Chapters and Levels[]

In traditional Doom games, levels can be categorized into two main types in the usual manner. The first is techbase style levels, which take place in a futuristic environment, typically within the industrial interiors or external areas of a facility built by the UAC. The second type consists of levels exuding a hellish atmosphere, usually set in infernal locations.

The Doom: Mercury Rising campaign operates similarly, complemented by other settings. Throughout the entire campaign, we can also encounter:

Levels set in underground tunnels and mines, dark places with a heavy atmosphere.
Levels inside a floating UAC facilities (specifically, in the Venus's upper atmosphere, or in spaceports high above the equator).
Worlds frozen in ice in the northern Mercurian regions.
Locations situated in the eternal twilight zone beyond the Mercury's polar circles.
And finally, one level set in the Cosmic Realm, as introduced in Doom: The Dark Ages.

The complete list of the Doom: Mercury Rising campaign levels, broken down by chapter, is provided below:

Codex Entries[]

The Doom: Mercury Rising campaign contains several CODEX ENTRIES in order to present the world of Mercury in 2141 in as much detail as possible. Due to this, the large amount of codex entries is divided into 3 chapters, and each chapter's codex entries are listed within each chapter’s own Wiki page.

Doom: Mercury Rising

Contents

Background[]

Development[]

Gameplay[]

Collectibles[]

Weapons / Equipment[]

Enemies[]

Plot[]

Chapters and Levels[]

Mercury Rising - Part One[]

Mercury Rising - Part Two[]

Mercury Rising - Part Three[]

Codex Entries[]

Timeline[]

Photos[]

Videos[]

Trivia[]

References[]