Bfg9000 (doom)

Cheat codes (PC)

• IDDQD — Invulnerability
• IDBEHOLDI — Temporary invisibility
• IDBEHOLDR — Temporary radiation suit
• IDBEHOLDS — Temporary berserk
• IDBEHOLDA — Temporary automap
• IDBEHOLDV — Temporary invulnerability
• IDBEHOLDL — Temporary light
• IDKFA — Full health, ammo, weapons, armor and keys
• IDFA — Full health, ammo, weapons, and armor
• IDCHOPPERS — Obtain the chainsaw
• IDCLEVxx — Warp to level ‘xx’, replace xx with number 01 to 19 to go the the level you want to go to.
• IDMYPOS — Displays your position and bearing
• IDMUSxx — Music select. ‘xx’ is the level who’s song you want.
• IDCLIP — No clip through walls

You don’t need the code to be typed with caps to enable the cheat.

Physically Based Rendering

Implementing Physically Based Rendering (PBR) in Doom 3 is a challenge and comes with a few compromises because the Doom 3 content was designed to work with the hardware constraints in 2004 and that even meant to run on a Geforce 3.

The light rigs aren’t made for PBR but it is possible to achieve good PBR lighting even with the old content by tweaking the light formulars with a few good magic constants. However I also want to support the modding scene to allow them to create brand new PBR materials made with Substance Designer/Painter or other modern tools so multiple rendering paths have been implemented.

PBR allows artists to create textures that are based on real world measured color values and they look more or less the same in any renderer that follows the PBR guidelines and formulars.

RBDOOM-3-BFG only supports the standard PBR Roughness/Metallic workflow.

Adding PBR is a requirement to make the new content look the same in RBDOOM-3-BFG as in Blender 2.9x with Cycles or Eevee and Substance Designer. PBR became the standard material authoring since 2014. With RBDOOM-3-BFG modders can work with modern tools and expect that their content looks as expected.

The PBR implementation is restricted to standard PBR using the Roughness/Metallic workflow for now. Specialized rendering paths for skin, clothes and vegetation will be in future releases.

Gaming / Graphics Related

• Physically Based Rendering using GGX Cook-Torrence as in other modern engines (UE4, Unity) and 3D authoring tools like Blender 2.93 or Adobe Substance
• Baked Global Illumination using Irradiance Volumes and Image Based Lighting that fix the pitch black areas
• Soft shadows using PCF hardware shadow mapping.
  All 3 light types (point, spot, parallel/sun) are supported which means parallel lights (sun) use
  scene independent cascaded shadow mapping.
• True internal 64 bit HDR lighting with filmic ACES tone mapping and gamma-correct rendering in linear RGB space
• Filmic post process effects like Chromatic Aberration and Dithering
• Bink video playback through libbinkdec (thanks to Daniel Gibson) or FFmpeg (thanks to Carl Kenner)
• Cinematic sequences can be skipped (thanks to Biel Bestué de Luna)
• Netcode fixes to allow multiplayer sessions to friends with +connect (manual port forwarding required)

Canceled VR support[edit]

According to Oculus VR, Doom 3: BFG Edition was initially supposed to include support for the Oculus Rift and be featured as a bundle-in with the device’s standard development kit. It was abruptly announced as canceled in the Rift’s Kickstarter Update 21 and contributors were offered Steam store credit instead.

It was later revealed that this cancellation was due to failure to reach an equity agreement with ZeniMax Media. This became a significant factor in the subsequent departure of John Carmack and the majority of the id tech team from the company as of . In a legal brief filed in the U.S. District Court of Northern Texas, ZeniMax maintained that an announcement of official support for the Rift in their products was never condoned by the company itself. This issue amongst others will be settled at trial.

Back End Rendering of Stencil Shadows

The RBOOM-3-BFG Edition GPL Source Code release includes functionality enabling rendering
of stencil shadows via the «depth fail» method, a functionality commonly known as «Carmack’s Reverse».

License

See LICENSE.md for the GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007

ADDITIONAL TERMS: The Doom 3 BFG Edition GPL Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU GPL which accompanied the Doom 3 BFG Edition GPL Source Code. If not, please request a copy in writing from id Software at id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

See LICENSE_EXCEPTIONS.md for all parts of the code that are not covered by the GPL.

Getting the Source Code

This project’s GitHub.net Git repository can be checked out through Git with the following instruction set:

The parameter —recursive is only required if you want to build RBDOOM-3-BFG with Vulkan support.

Existing repositories can be updated manually:

Compiling on Windows

1. Download and install the Visual Studio 2017 Community Edition.

2. Download and install the latest CMake.

3. Generate the VS2017 projects using CMake by doubleclicking a matching configuration .bat file in the neo/ folder.
   Recommended in this case is

4. Use the VS2017 solution to compile what you need:
   RBDOOM-3-BFG/build/RBDoom3BFG.sln

Gaming Related

Optional if you want to use FFmpeg

1. Download ffmpeg-4.2.2-win64-shared.zip from ffmpeg.zeranoe.com/builds/win64/shared

2. Extract the FFmpeg DLLs to your current build directory under RBDOOM-3-BFG/build/

Compiling on Linux

1. You need the following dependencies in order to compile RBDoom3BFG with all features:

   On Debian or Ubuntu:

   On Fedora

   On ArchLinux

   On openSUSE

   You don’t need FFmpeg to be installed. You can turn it off by adding -DFFMPEG=OFF and -DBINKDEC=ON to the CMake options. It is enabled by default because the bundled libbinkdec is slow during development if compiled for Debug mode.

2. Generate the Makefiles using CMake:

3. Compile RBDOOM-3-BFG targets with

Compiling on macOS

1. You need the following dependencies in order to compile RBDoom3BFG with all features:

   You don’t need FFmpeg to be installed. You can turn it off by adding -DFFMPEG=OFF and -DBINKDEC=ON to the CMake options. For debug builds FFmpeg is enabled by default because the bundled libbinkdec is slow during development if compiled for Debug mode. For release, retail and universal builds FFmpeg is disabled and libbinkdec is enabled by default.

2. Generate the Makefiles using CMake:

   For command line builds:

   For Xcode builds:

   Depending on which package manager you install (Homebrew or MacPorts) you may need to change the openal-soft library and include paths specified in the cmake shell scripts. For single architecture builds (debug, release, retail) the default openal-soft paths are set for Homebrew on x86, while for universal builds the default paths are set for MacPorts on x86 or Apple Silicon. If you want to build using the single architecture shell scripts (debug, release, retail) on Apple Silicon, you will need to change the openal-soft paths from to either (Homebrew) or (MacPorts).

3. Compile RBDOOM-3-BFG targets:

   For command line builds:

   For Xcode builds double click on RBDOOM-3-BFG/xcode-opengl-<buildtype>/RBDoom3BFG.xcodeproj and start the build. The generated Xcode project file is pre-configured with the correct targets and build settings.

Tactical analysis

The BFG 9000 fires a green burst of plasma, damaging enemies near the projectile during flight and vaporising targets upon impact, as well as causing significant splash damage to enemies standing in the vicinity of the projectile’s explosion. The damaging bolts do anywhere from 120 to 1 damage a shot at 100ms, doing 1200/1 dps. Because of the projectiles slow speed and large radius it will do major damage before the enemy leaves the area. A direct hit does 6000 damage. Thus, the BFG 9000 is the most powerful weapon in the game, as it is able to kill any non-boss creature in a single direct hit.

However, bosses can be stunned with one direct hit for a few seconds, which can be used to break up an attack. The weapon is very useful in dangerous situations or against a large group of powerful creatures.

Unlike most weapons, no modifications can be added to the BFG 9000, nor can any improvements be made. It also holds up to 3 shots, however there is an upgrade that can be made for enemies to have a small chance of dropping BFG ammo. If the player fully upgrades all weapons, the Praetor Suit, and has fully upgraded the health, armor, and ammo subsystems, a 4th shot for the BFG 9000 will be unlocked. It is unknown if this is true.

BFG ammunition takes the form of green ringed orbs that give off a low whirring noise. They are actually not particularly rare in most levels.

The BFG is one of the 3 power weapons available in Multiplayer, where it is an excellent way to kill demons or clear large areas of enemies. As with the Chainsaw and the Gauss Cannon, the Weapon Mod allows the user to see enemies through walls. The damage is 15/1 per bolt with 100ms, so it does 150/10 dps. A direct hit does 275 damage.

The following instructions are primarily intented for Linux users and all hackers on other operating systems.

To play the game, you need the game data from a legal copy of the game.

Currently this requires a Windows installer, whether that be the GOG installer or by using Steam for Windows.

Note: the original DVD release of Doom 3 BFG contains encrypted data that is decoded by Steam on install.

Then you can download Doom 3 BFG with

NOTE that we’ve previously recommended using download_depot in the Steam console to install the game data. That turned out to be unreliable and result in broken, unusable game data. So use SteamCMD instead, as described above.

Once Wine is installed and configured on your system install Doom 3 BFG edition using the downloaded installers from gog.com:

(there will be several .exe files from GOG, make sure all of them are in the same directory)

Once this is complete, by default you can find your Doom 3 BFG «base/» directory at «.wine/drive_c/GOG\ Games/DOOM\ 3\ BFG/base».

Note that you may want to add the following line to the bottom of the default.cfg in whatever «base/» directory you use:

set sys_lang «english»

This will ensure the game and its menus are in english and don’t default to something else. Alternatives include:

• set sys_lang «english»
• set sys_lang «french»
• set sys_lang «german»
• set sys_lang «italian»
• set sys_lang «japanese»
• set sys_lang «spanish»

Anyway:

1. Install Doom 3 BFG in Steam (Windows version) or SteamCMD, make sure it’s getting
   updated/patched.

2. Create your own Doom 3 BFG directory, e.g. /path/to/Doom3BFG/

3. Copy the game-data’s base dir from Steam or GOG to that directory
   (e.g. /path/to/Doom3BFG/), it’s in
   /your/path/to/Steam/steamapps/common/DOOM 3 BFG Edition/base/
   or, if you used SteamCMD or GOG installer with Wine, in the path you used above.

4. Copy your RBDoom3BFG executable and the optional FFmpeg DLLs (if Windows FFmpeg enabled) to your own
   Doom 3 BFG directory (/path/to/Doom3BFG). Your Doom 3 BFG directory now should look like:

   /path/to/Doom3BFG/

   • RBDoom3BFG (or RBDoom3BFG.exe on Windows)
   • avcodec-58.dll (Windows FFmpeg only)
   • avformat-58.dll (Windows FFmpeg only)
   • avutil-56.dll (Windows FFmpeg only)
   • swresample-3.dll (Windows FFmpeg only)
   • swscale-5.dll (Windows FFmpeg only)
   • base/
     • classicmusic/
     • _common.crc
     • (etc)

5. On macOS the RBDoom3BFG executable will also search for game data within an app bundle’s relative path ../Resources/base and, as a last resort, within the absolute path /Applications/RBDoom-3-BFG.app/Contents/Resources/base. In addition, if you want the game to be standalone without dependencies on pre-installed dynamic libs, you can use macdylibbundler to bundle all external dylib dependencies into the app bundle (see https://github.com/auriamg/macdylibbundler or simply install via «brew install dylibbundler» or «sudo port install dylibbundler»). For example, the following command will copy all external dynamic library dependencies to the Contents/libs directory of the game’s app bundle and adjust the rpaths within the RBDoom3BFG executable and copied dylibs.

   After running dylibbundler you must re-sign the modified executable and dylibs if planning to run on Apple Silicon machines. The output of dylibbundler will indicate which dylibs (if any) require re-signing. This code signing step is not needed for x86-based Macs.

6. Run the game by executing the RBDoom3BFG executable.

7. Enjoy

8. If you run into bugs, please report them, see

Weapon schematics[edit]

The BFG in Doom 3 functions in a largely different way from its Doom counterpart. Comparing the weapons visually, the Doom 3 version is more compact, lacking a harness, has a shiny smooth metallic framework versus the original’s rough design studded with various technological implements, and totally lacks the corrugated aperture that was shared with classic Doom’s plasma gun.

The BFG 9000’s projectile consists of a computer chip contained within a massive ball of relatively slow-moving green plasma, the strength of which is determined via a charge-based system: holding down the trigger causes the weapon to charge through four different power levels for a more powerful shot, the status of the charge being displayed on the weapon’s integrated monitor (which also displays the ammo count, dispensing with a game HUD, just like plasma gun, chaingun, and machine gun). Caution must be utilized, as if the weapon is charged beyond the fourth level, the weapon will explode and will instantly kill the player wielding it. This is referenced in-game as a glitch in the prototype weapon’s design which was still being worked on by the UAC’s tactical arms research and development team.

The projectile’s embedded computer chip contains a sophisticated identification friend or foe system, and, similar to the BFGs found in the Quake series of games, fires green energy rays at opponents which debilitate them prior to the detonation of the plasma projectile. The damage of these rays is around ten points per second. If the computer core in the projectile is destroyed before the projectile impacts with a surface or soft target, the explosion will be suboptimal, though can still deal considerable damage at close range. This makes use of the plasma gun in countering an enemy’s BFG shots critical.

The effects of the weapon are devastating: a projectile charged at the lowest level can obliterate any weaker monsters, whereas a fully-charged shot will kill any monster with health equal to or less than the Vagary. «Elite» monsters with high hit points such as the Hell knight or the mancubus generally require a double or triple-charged shot to kill, and this weapon is ideal for dispatching arch-viles quickly when the Soul Cube and Artifact are not available.

Unlike in the classic Doom and Doom II, the BFG 9000 in Doom 3 no longer uses the same ammo as the plasma gun, but has its own type of cells instead. The BFG cell is a small green cylinder with an actively vibrating sphere inside, with an appearance similar to an atom, and holds four charges. Unlike in Doom II, BFG cells are extremely rare and often placed in relatively obscure locations, and it is therefore recommended to use the weapon sparingly.

Research and development[edit]

The BFG-9000 was developed in the Advanced Research Complex’s BFG Division, with a single initial prototype being produced. It was evolved from the first successful Argent weapon design, the plasma rifle, and is distinguished by making the most efficient use of the energy form yet known. The streams of Argent energy released by the weapon are attracted by other sources of the energy, which are typically demons or humans with Argent beacon implants, and thus behave in a guided manner. Upon contact, the streams release all their stored energy in a fraction of a second. This boils the fat and bodily fluids of such targets, which usually results in a subsequent full-body explosion.

Subsequent prototype versions of the weapon behaved unpredictably and were prone to releasing lethal radiation, resulting in disasters during testing. These included the generation of Argent spheres that released energy waves on impact and lasers that could cut through virtually anything, each with potentially useful but misdirected effects.

After being deployed into production, it was declared the «greatest triumph of the Ascension» by the UAC cult on the Mars base, practically being worshipped as a representation of the twisted philosophy being espoused in the period before the demonic invasion was unleashed by Olivia Pierce. Its use was restricted to Tier 3 advocates, and those who could not yet use it were suggested to either envision the day they would gain access, or, most unbelievably, that they might get the chance to be killed by its «majestic» and «invigorating» touch.

The BFG in other id Software games

The BFG in Doom 64.

Doom 64’s BFG pickup sprite.

• Doom 64 includes a slightly revamped version of the BFG. Upon being fired, it will make a computerized whirring sound increasing in pitch until the projectile is shot out. When the projectile hits an enemy or wall, it will create a cone-shaped field of damage from its detonation point back to the player, killing or hurting any monsters in its path.
• Quake II features the BFG 10K. This was the first attempt to rework the BFG mechanics, and set the standard for future BFGs. Rather than the complicated system of firing traces out of the player after the projectile explodes, the traces are fired out of the projectile as it moves, dealing damage-over-time to nearby enemies. The projectile sprites are exactly the same as Doom’s. Unlike Doom’s BFG, however, a point-blank blast will kill the player as well as their intended target.
• Quake 3 Arena included a new version of the BFG 10K that works considerably different then its previous incarnations. It fires explosive plasma projectiles at a high rate of fire and has a more streamlined shape.
• Doom 3 includes a redesigned version, see BFG 9000 (Doom 3). It can be charged up for a more powerful shot, but if charged for too long it will «overload,» failing to fire and dealing a large amount of damage to the player. It is otherwise mechanically similar to the Quake II variant.
• The BFG also appears in Doom RPG, where it is named BFG-9000.
• Rage includes a weapon called the Authority Pulse Cannon, which normally acts as a sort of energy-based minigun, but also features the ability to fire an alternate ammo type called «BFG Rounds», which do devastating damage to targets within range.
• The BFG appears in Bethesda Pinball’s Doom table as a collectible weapon that is the most powerful of 8 possible weapons. One shot from the BFG instantly annihilates a demon wave, and an extra ball is granted when it is first obtained.

Changes

The BFG Edition of Doom 3 is different in multiple ways from the original Doom 3:

• Game is compatible with modern operating systems, including Windows Vista and Windows 7.
• Steamworks integration with Steam Achievements.
• Xbox 360 and PlayStation 3 versions almost comparable to the PC version.
• EAX enhanced sound quality removed.
• Advanced keyboard function mapping removed.
• Support for 3D TVs, High Resolution and Ultrawide monitors, and the Oculus Rift.
• Improved performance.
• Constant 120Hz game engine for ultra smooth animations and gameplay.
• Minor graphical improvements (Particularly removed texture «seams»)
• Improved texture resolution.
• «Shoulder-mounted» flashlight usable with weapons.
  • Original handheld flashlight removed from game.
  • Hazmat suit sequence from Resurrection of Evil removed from game.
• Improved lighting effects.
• Light from the flashlight and enemy projectiles can now project shadows.
• Muzzle flashes no longer create light sources.
• HUD crosshair replaced with laser sight when playing in 3D mode.
• Checkpoint saving (an option to disable checkpoints has been included with a patch).
• PDA has a new layout for widescreen display.
• id Tech 4 engine updated with improvements from id Tech 5.
• Compatible with existing texture and sound Doom 3 mods.
• Easy difficulty is made easier by providing more health, ammo and armour to the player.
• Simplified menus.
• Narrower Field of View (FOV).
• Zoom function removed (narrower FOV results in more zoomed default view).
• Maximum ammo capacity for most weapons has been slightly adjusted.
• Ammo pickups provide more ammo, to reduce the need for ammo hunting.
• Armor no longer decays once it exceeds 100.
• Only 14 save slots available, plus one autosave slot and one quicksave slot. Save slots are shared across all three campaigns (Doom 3, Resurrection of Evil, and The Lost Mission).
• Cutscenes are now unskippable.
• A few minor changes to scripted events; i.e., the imp behind the windows in Administration simply attacks the player instead of walking away.
• A lot of enemy encounters in original Doom 3 and Resurrection of Evil got cut, for example, encounter with hellish version of boney zombies in Hell level of original Doom 3.
• The Maledict in Resurrection of Evil no longer summons Forgotten Ones during its boss fight.
• Arcade games Sarge’s Big Game Hunt and Martian Buddy Blaster in Resurrection of Evil are replaced with Super Turbo Turkey Puncher 3

  The secret BFG 9000 tied to the Martian Buddy Blaster game has been removed.

  .

The included versions of Doom and Doom II also have some changes:

• Includes the recently released Doom II eight map expansion «No Rest for The Living».
• Steam Achievements.
• Runs at 1080p resolution on consoles.
• Runs at desktop resolution on PC with minor graphical improvements.
• Improved, more responsive mouse and keyboard controls.
• Improved and smoother animations at 120Hz.
• Improved controls for Windows Vista and Windows 7.
• Improved weapon sound quality and MIDI music quality.
• Removal of the red cross symbol on medpacks and berserker packs (the International Red Cross have been complaining about what they regard as the abuse of this symbol in video games). Instead, the pickups bear a red and white medicine capsule.
• Removal of all Nazi references, including the Hakenkreuz, Hitler’s portrait, furniture and textures (to make the game legal in Germany).
  • Map ‘Wolfenstein’ (map31) and map «Grosse» (map32) have been renamed to «IDKFA» and «Keen» respectively.
  • Changed unit IDs in maps 31 and 32.
  • Changed textures in map 31.
  • Changed music in maps 31 and 32.
• All cheats require enabling the console from outside the game by adding a parameter to the default.cfg file.
• The «fast monsters» parameter has been modified in the Nightmare skill level. Monsters remain just as aggressive as in the original Nightmare mode, but neither demons nor enemy projectiles travel at increased speed compared to the lower skill levels.
• The Tower of Babel is no longer shown being progressively built on the intermission screen between levels.

The .WAD files for the BFG Editions of Doom and Doom II do work with source ports like Zandronum and ZDaemon as well as with Doomsday and ZDoom. The Doom II expansion «No Rest for The Living» also works on these source ports when using Doom II as the main WAD and the NERVE wads used for the map information.

Tactical analysis

Without a doubt the most powerful weapon in the game, the BFG9000 is capable of causing damage to a single enemy for more than 1700 hit points.

The effects of the weapon are devastating; a single-charged projectile can obliterate any smaller demon. Even if the shots are not directed towards the target, the powerful rays emitted from the projectile will cause continuous damage over 200 (over 10 points per second), making it deadly for even the most agile demon like the Tentacle Commando. A fully-charged shot will kill any monster up to a Vagary. The most powerful monsters with a lot of hit points such as the Hell Knight or the Mancubus generally require a double or triple-charged shot to kill, and this weapon is ideal for taking out Arch-viles quickly, when the Soul Cube is not available.

The weapon’s destructive capability is unmatched (minus the Soul Cube), but can also act as a double edged sword; firing at a monster up close will severely damage the player due to the weapon’s blast radius. In addition, the weapon is very «fragile» as it can be prone to overheating if charged for too long, killing the user instantly.

As the BFG’s charged shots travel very slowly, this will give enemies more opportunity to attack you, even while they take damage from the rays. Therefore do not stay at one place while waiting for the shots to find their mark, especially when fighting against enemies with high HP like the Hell Knight.

The BFG is recommended for medium to long-range combat. As BFG cells are very rare, its usage should be limited to areas where stronger enemies like the Hell Knight and Arch-viles are present. The Caverns in the later levels serve as the best area where the BFG can come into great use, due to high abundance of these kinds of enemies and BFG Cells.

Trivia

• A glitch exists that allows the player to vastly increase the damage of traces from the BFG: to perform it, the player must aim the BFG to miss, then pull up the radial weapon menu. While this slows down all action on-screen including the BFG’s projectile, the trace continues to deal damage in real-time. Increasing the frame rate (by turning down visual settings and disabling Vsync) can increase this still further: this is often used in speedruns to quickly kill the Cyberdemon boss.
• The overall appearance and function of the BFG 9000 appears to combine many features of previous BFG iterations; its overall design appears to be based on the movie incarnation (the Bio Force Gun 3.14) as the bottom half of the gun with the classic design being attached to the top and providing the color scheme. Its projectile behaves similarly to the Doom 3 incarnation (but with a faster flying speed).
• Some of the descriptions given for the BFG test rooms seem to describe how the BFG functioned in earlier Doom games.
• The UAC labs seem to treat the BFG as an object of worship in and of itself, demanding all bow to the weapon’s inherent majesty. Indeed, it’s one of the most heavily-guarded objects in the entire complex; even the Doom Slayer’s sarcophagus wasn’t as heavily guarded.
• BFG cells vary widely in how common they are. While very rare in the part of Hell the player explores to get the Crucible, they are plentiful in the other four levels that contain it, and use of the BFG is in fact encouraged in the last level. This may be intended as a compensation for the BFG in Doom 3, which suffered from being sidelined by the Soul Cube as that game’s most powerful weapon. Furthermore, this game’s BFG will not splash-damage the player, unlike the BFGs in classic Doom and Doom 3.

Video Disk — BFG 9000 Briefing

Creator: UAC Advanced WeaponsDate: 10/10/45

Informational video on the BFG 9000

Representing the pinnacle of UAC research and design, the BFG 9000 is the most advanced firearm ever designed. Fully self contained and deployed as a handheld platform, it is capable of an excessive amount of firepower. The BFG 9000 contains sophisticated friend or foe technology that discriminates targets in real time.

Each projectile contains a small but very powerful computer core that actively maintains targeting and delivers a stream charge down each beam to soften targets before detonation. The detonation stage of the projectile is devastating. Targets within 15 meters of the flashpoint are not likely to survive.

While not recommended for small quarter combat, the BFG 9000 is ideal in the field and against multiple targets. The only foreseeable defense is small arms ballistics. If the projectile is destroyed before exploding, the computer core cannot process the final fusion reaction, resulting in a less than optimal detonation.

For more information, contact the UAC’s Advanced Weapons Department.

Combat characteristics

The BFG9000 shooting a plasma ball in MAP32 of Hell Revealed.

When the trigger is pulled, there is a pause of 30 tics (about 0.857 seconds) before a green and white plasma ball is ejected. 40 plasma cells will be consumed, and if the large plasma ball hits a solid object, it explodes and causes 100-800 hit points of damage to the target, in round multiples of 100.

After a further pause of 16 tics (about 0.457 seconds), additional damage is calculated: 40 invisible tracer rays are emitted by the player in a cone-shaped area (about 45° half-angle) in the direction the plasma ball was fired (if the player has turned around, the direction of the rays does not change — they are still traced in the direction of firing of the original plasma ball; on the other hand, if he has moved to another location, their origin moves along with him). Each ray causes 49-87 points of damage if it hits a solid object within 1024 map units. Even Cyberdemon and Spiderdemon, which are immune to blast damage, are affected by these rays.

Therefore, the minimal damage of the weapon is 49 points (if an object is hit by one ray and not the plasma ball) and, hypothetically, the maximal damage is 800 + (40 × 87) = 4280 points (if the plasma ball hits an object for full damage and all 40 tracers also hit the object for full damage). However, even should all 40 rays and the energy ball hit a single target, that much damage can still never actually be inflicted due to the periodicity of the simplistic pseudorandom number generator used by the Doom engine.

Contrary to section 3H of the , the tracer code does not include horizontal auto-aiming (although, like any bullet attack, each tracer can auto-aim vertically).

Because the BFG projectile does not cause standard blast damage, it is safe for the player to use at point-blank range. In fact, this is often the preferred method of usage against large monsters, as this allows more of the tracer rays to strike a single target for concentrated damage. Conversely, because each ray can strike a different target, a large group of monsters can be damaged by the tracer rays if the weapon is fired from a moderate distance.

Gameplay

Doom is a first-person shooter with a background setting that mixes science fiction and horror (of the weird menace style), presented in the form of three episodes, each taking place in a separate general location and played separately. The primary objective of each level is simply to locate the exit room that leads to the next area (conveniently labeled with a red EXIT sign), while surviving all hazards along the way. Among the obstacles are monsters, pits of radioactive waste, ceilings that descend to crush the player, and locked doors for which a key or remote switch need to be located. The levels are sometimes labyrinthine (the automap is a crucial aid in navigating them), and feature plenty of hidden rooms that hold powerups as a reward for players who explore thoroughly. A tally screen at the end of each level (except the last of each episode, which describes part of the plot) helps players aiming for additional objectives, such as clearing the levels of monsters or finding secret areas.

Aside from the single-player game mode, Doom features two multiplayer modes usable over a network: co-operative mode, in which two to four players team up against the legions of hell, and deathmatch mode, in which the same number of players fight each other.

The enemy monsters are Doom’s central gameplay element. There are 10 types of monster, including possessed humans as well as demons of different strength, ranging from weaker but ubiquitous Imps and red, floating Cacodemons to the bosses, which tend to survive multiple strikes even from the player’s strongest weapons. The monsters generally exhibit very simple AI, and thus most cases must outnumber the player to triumph (although great numbers can sometimes prove counterproductive due to monster infighting).

Doom’s weapon arsenal was highly distinctive in 1993 and eventually became prototypical for first-person shooters. The player starts out armed only with a pistol, and brass-knuckled fists in case his ammunition runs out, but larger weapons can be picked up: a chainsaw, a shotgun, a chaingun, a rocket launcher, a plasma gun, and the immensely powerful BFG9000. There is a wide array of additional powerups, such as a backpack that increases the player’s ammunition-carrying capacity, armor, medical supplies to heal injuries, and strange alien artifacts which can turn the player invisible or boost his health and / or armor beyond its normal maximum.