The game is divided into chapters, each of which involves Batman stopping the machinations of a prominent villain from his Rogues Gallery and eventually facing the villain as a boss.
Batman Doom remains one of the most acclaimed mods for Doom II, in part due to its Genius Programming, which is apparent to anyone with expertise in Doom editing; while modern source ports give the modders wider flexibility and freedom, the original Doom engine is notoriously inflexible, and yet ACE Team have managed to achieve some truly mind-bogglingly difficult tricks with it.
It is available for download here.
Because this mod relies heavily on complex DeHackEd patches, it doesn't play nicely with many modern source ports unless they're extremely vanilla-focused, such as PrBoom or the intended Crispy Doom. However, a fan-made patch exists for ZDoom-based source ports that rewrites most of the DeHackEd patches in equivalent DECORATE scripts in order to fix the compatibility issues, as well as a "Plus" version that adds new enhancements to the mod.
A project called "Batman Doom: Reborn" is also in the works which aims to completely remaster and modernize the mod with the GZDoom source port in mind.
This mod exhibits the following tropes:
- Absurdly Short Level: The Batcave levels, which serve solely to replenish your supplies a bit and brief you on the next villain you'll be up against. You can complete each of these levels in seconds by approaching the Batmobile. However, there's an unique secret hidden in the Batcave each time which can take more time to find.
- Action Bomb: The Penguin's robotic Penguin Bombs, which blow up when they're close. In the last boss fight with the Penguin, they keep spawning and coming at you from all sides while you're trying to deal with the boss.
- Amusement Park of Doom: The "House of Fear" level is set in a haunted house attraction, complete with Creepy Circus Music. It's a bunch of twisty corridors with false doors and a frequent fire trap or two (as well as an occasional scream to give you a Jump Scare).
- Arm Cannon: By necessity—Doom's firearm weapons need to be somehow translated into Batman terms, after all—most of Batman's ranged weapons in this mod are gun-like weapons, set in glove-like frames worn on Batman's arm. They include the Blastguns and Azrael's Glove (both of which fire some unspecified kind of "shells"), the Shuriken Glove (a rapid-fire weapon which oddly enough uses Batarangs as ammo), and the Flamethrower which is, well, exactly, what you'd expect.
- BFG: In the boss fight with Two-Face, he fights Batman with a rocket launcher.
- Blatant Item Placement: Even more so than in Doom, possibly. There's no particular reason why you can find, say, boxes full of batarangs or special anti-radiation Batsuits inside random buildings in Gotham - even Batman's typical Crazy-Prepared attitude wouldn't let him place these deep inside the lairs of criminal masterminds.
- Bonus Stage: During your first boss fight with the Scarecrow, mayor Kroll sits nearby, tied to a ticking bomb. If the bomb explodes, the level ends and you go to the next one (map16) like normal. But if you manage to actually defeat Scarecrow before the explosion, you go to map31. It's a big, empty (and thus somewhat creepy) city map where you're trying to collect a bunch of random bonuses before you can access the exit and continue onto map16. This is also where you can access the Secret Level.
- Boss-Only Level: The final level is a short map, consisting of basically two rooms, which features a duel against Bane in the ruins of the Batcave.
- Boss Rush: The two penultimate levels take place in the Arkham Asylum in the middle of an outbreak (mirroring part of the Knightfall storyline). All the inmates from Batman's Rogues Gallery — which is to say, the bosses you've fought throughout the game — are fought one by one throughout these two levels.
- Cool Shades: Shotgun Thieves, Slum Lords, and Snipers all wear sunglasses.
- Creepy Circus Music: The "Scarecrow" track, which plays on the "House of Fear" level set in a haunted house attraction.
- Did You Actually Believe...?: In "Gas Trap", you have to search a hospital for a switch to prevent the release of poison gas. A few minutes in, you do find a switch labelled "GAS SWITCH", but pressing it just releases some Penguin Bombs and a sign reading "DID YOU REALLY THINK IT WOULD BE THAT EASY?"
- Die, Chair, Die!: Chairs can be wrecked by Batman or the enemies. The same thing applies to the paper doors in the "House of Fear" level.
- Down the Drain: Shows up very quickly, as soon as you finish the first mission and the game proper begins ("Follow Killer Croc through the sewers"). Like in most such examples, the sewers are green, drab and moist, with enemies leaping at you from under the water, and several catwalks above big water tanks.
- Everyone Owns a Mac: Apple Macintosh computers can be seen in many places throughout the game, including the Batcave. The Computer Area Map power-up is even a Macintosh. May count as a Console Cameo as it was originally released for the Mac version of Doom.
- Fauxlosophic Narration: A few text screens pop up during the game, filled with Batman's musings about how he's "the chosen one" to fight evil. They don't have much to do with the actual game. On the other hand, if you assume that Batman in this game is actually Azrael, it's pretty in-character for him to brood like that.
- Fire-Breathing Weapon: Batman can obtain an arm-fitted flamethrower that functions like the Plasma Rifle in Doom. Meanwhile, the Flamethrower Dude enemies are armed with traditional flamethrowers. Both of these weapons have a quite limited range.
- Fisticuffs Boss: Bane, the end boss. You are forced to pick up a special gauntlet and you cannot switch to any other weapon. If you try to switch out, the fight becomes Unwinnable as you are rendered completely helpless.
- Friendly Local Chinatown: One of the levels... sans the "friendly" part. Buddhist iconography, paper lanterns and shuriken-tossing Asian thugs abound.
- Game-Breaking Bug:
- Attempting to play the mod in Skulltag or Zandronum results in certain enemies apparently becoming voodoo dolls who, if you kill them, automatically kill you in return by way of telefragging, even if you're in god mode. Thankfully, the enemies that do this are rare in comparison to the "safe" ones... but this still makes the game unwinnable because one of them happens to be the final boss, Bane. The seventh weapon is also unusable, as it takes up ammo even though it's supposed to have infinite ammo, making the final fight with Bane completely unwinnable. The latter bug seems to be fixed in newer dev builds of ZDoom (Skulltag and Zandronum are based on a rather old version).
- The mod itself also doesn't take kindly to misusing the autoload function or the "-file" command parameter of ZDoom-based source ports to load the WAD and patch files automatically instead of dragging and dropping them to the executable, resulting in erratic and glitchy behavior that would never happen otherwise.
- The Joker will suddenly disappear when you beat in him in ZDoom-based source ports in maps 24, 25, and 29, and the script that takes you to the next level doesn't work, forcing you to use a cheat to advance to the next level.
- A fan-made patch for ZDoom-based source ports aims to fix these issues, but the 0.4 version of the "Plus" patch renders some levels unwinnable unless you use cheats due the increased view height that prevents you from entering certain rooms, and outright disabling the ability to jump and crouch. This was fixed in newer versions of the Plus patch.
- The PC version suffered a bug related to the DOS version of DeHackEd that prevented switching from the fists. This prompted the devs to recommend Boom as the port of choice, which wound up causing one of its own as detailed below.
- Zeke's molotov cocktail attack originally spawned a grid of fire in the Mac version rather than the single flame in the PC version,note as it used a recursive loop of the Pain Elemental's death frames, which normally spawns Lost Souls. The vanilla DOS and Mac versions had a hardcoded limit of 21 lost souls, preventing Pain Elementals from spawning more than that, but this caused a crash in Boom as well as later ports that removed the soul limit, resulting in the effect being nerfed into a single flame. As the Mac version was AWOL for a significant period of time, this was not discovered until late 2018, and a DeHackEd patch has since been made that restores the original behavior.
- Game-Over Man: In the final level, losing to Bane or trying to switch to a ranged weapon will cause a Non-Standard Game Over with Bane's image covering the screen alongside text telling you "YOU FAILED TO FIGHT BANE WITH YOUR FISTS".
- Guns Akimbo: The Tally Man fights Batman with dual revolvers. Batman also dual-wields "blastguns" on both his arms.
- Hub Level: Each chapter is punctuated by a brief visit to the Batcave, where you can resupply yourself and look at the Batcomputer to see who's causing trouble next before heading out to deal with them. It's only a hub insomuch as the Doom engine without Hexen's additions can do it; each visit is technically a separate level, just copied and pasted over again, the only changes being what texture appears on the computer's screen and the addition of a single secret area, which changes each time.
- Joke Level: The Secret Level "No comment...", which is set in a bizarre, surreal environment and features flying eye monsters as enemies.
- Lost in the Maize: One such maze pops up near the beginning of the level with the Scarecrow boss fight. It's full of gangsters and even spotting the passages is a problem, though the automap helps. Once you're past this part, the rest of the level is thankfully free of the view-obscuring maize.
- Mind Screw: The Secret Level, called simply "No Comment..." or "Weird!", and both names fit. As the cheesy theme song of the campy 60's show plays in the background, you fight giant flying eyes on a island floating in black void, made out of flesh with trees with half-melted clocks growing out of it, and then enter the (literal) mouth of a meat pyramid to exit the level.
- Molotov Cocktail: Zeke, a kind of a Mook who looks like a fat trucker with a big beard, uses these. In the PC version, the Molotovs they throw are actually pretty harmless due to their short range - as long as you keep your distance and don't walk into a fresh Molotov still burning on the ground (they disappear after about a second), you're safe. In the original Mac version they instead create a much larger and more dangerous grid of flames.
- Monster Clown: Apart from the Joker himself, the mod features rather tough mooks dressed in mime/clown attire who throw darts at you. They show up in both the Scarecrow's and Joker's chapter.
- Never Trust a Title: The song that plays in the Batcave is "Streets of Gotham II". The Batcave levels are nearly the only levels where you aren't out on the streets.
- Non-Standard Game Over: During the fight with Bane, if you try to switch to a different weapon instead of fighting him in melee, you become unable to attack at all. A taunting message ("You failed to fight Bane with your fists") is prominently displayed on the screen. You can still run around, so it's not precisely a game over, but the fight becomes Unwinnable.
- Outrun the Fireball: In the end of the "Axis Chemicals" level, you press a switch that causes a huge wall of explosions to chase you down a street all the way to the Batmobile, all while you're trying to avoid pesky landmines on the way.
- Player Headquarters: The Batcave levels. Since it's a Doom mod, you cannot go there anytime you want to, but after defeating each end-of-chapter boss you return to the Batcave where you find some supplies. More interestingly, the Batcave has a different, cleverly hidden secret area each time you revisit it.
- In the level where you fight Two-Face, there's a room where a TV is playing Mortal Kombat with Scorpion fighting Goro.
- The Joker's levels are all references to scenes from Batman (1989), with the first being set in Axis Chemicals the last being set at the Gotham Cathedral.
- Slasher Smile: Batman dons one after picking up the invincibility power-up or when he's in God Mode. He's also seen with a smile-like grimace on the title screen.
- Standard FPS Guns: The Dark Knight's various gadgets function similarly to Doomguy's arsenal of weapons, but some were modded to handle differently. One of the new weapons, the "smoke bombs", fits into the "grenade" archetype (although they are a bit awkward to use, being essentially projectiles subject to gravity in an engine that wasn't designed with the idea of gravity-affected projectiles). The basic weapon, the Batarang, is an aversion of the usual trope — unlike in typical FPSes, it's not a pistol variant but rather a thrown projectile.
- Stock Sound Effects: Many of the sound effects are taken from Marathon or the Mortal Kombat game.
- Strapped to a Bomb: Mayor Kroll gets tied to a chair with a bomb tied to him. There's a time limit in which to save him, and if you take too long (or shoot him yourself), you miss out on the bonus level.
- Timed Mission: The level "Gas Trap" is set in a hospital where you have a few minutes to find the button that turns off emitters of poison gas. If you don't make it in time, the gas will be released and you will rapidly choke to death.
- Wind-Up Key: The walking penguin bombs have a golden wind-up key on their backs, which spins as they walk.
- Wolverine Claws: Doom's Imps are replaced by "Cheungs", long-haired Chinatown mooks who use both metal claws and thrown shurikens against you.