Doom Roguelike Enemy Analysis: John Carmack (0.9.9.7/0.9.9.8)

HP: 260/290/340/410/500 (250 base, plus 10*difficulty level squared)

Protection: 5

Ranged Accuracy: +12

Melee Accuracy: +8

Ranged Damage: 6d6 Fire

Melee Damage: 1d3 (+15) Melee

Speed: 100%

Inventory: Rocket ammo*30, plus his Rocket Launcher (Technically)

Experience: 0

Danger: N/A

Minimum floor: N/A

Maximum floor: N.A

Experience per Danger: N/A

Can open doors, equip Armor, and pick up and use Medpacks, Phase Devices, and Homing Phase Devices. Immune to Acid and Lava on the ground, as well as knockback and explosion damage.

If injured while unable to see Doomguy, summons 8 Barons of Hell in a random, circle-like formation around Doomguy. (These Barons are worth full experience) Also intermittently summons 8 monsters around himself, with the type being based on how little HP he has remaining: in order, he summons Lost Souls, Cacodemons, Hell Knights, Barons of Hell, and finally Revenants as his HP gets lower. (These summons are not worth experience)

Immune to knockback. Fires missiles from beyond even Cateye range. Intermittently teleports to a random location in Doomguy's sight.

Evasion: Base of 30%, plus 5% per tile of distance, making for a maximum of 70%

Attack chance: ??

Yep. John Carmack.

This is of course a callback to an easter egg in Doom II, where the mechanical weakpoint of the final boss is a depiction of John Romero's severed head; so too does Doom Roguelike secretly have another ID developer as a boss!

The details are pretty different, of course; Romero's head wasn't meant to be seen by players, and you can get the 'full Doom experience' without ever learning of its existence, whereas Doom Roguelike will, if you defeat the Spider Mastermind 'incorrectly', hint that you missed something, and only awards you a 'standard' victory, further hinting there's some nonstandard victory to hunt for.

If you're not aware of what that victory is and want to puzzle it out yourself, maybe come back to this post after you've managed that feat.

I'll wait.

Okay, for those of you who don't mind spoilers, time to explain it!

A successful 'full' victory has two key components: you need a nuke, and ideally you also have the Lava Element. You get the Lava Element by clearing Mount Erebus/The Lava Pits, and specifically by killing the Lava Elemental, whereas you get the nuke by hitting up Limbo/The Mortuary. Well, a makeshift nuke: the Nuclear BFG on the map.

Both (pairs of) Special Level are strictly optional to enter, mind. They're the reliable ways to trigger access to John Carmack, but it's possible to find a regular nuke on a random regular floor, or to find a Nuclear BFG or Nuclear Plasma Rifle at random. Similarly, it is possible to simply have an Invulnerability Sphere spawn on floor 23, close enough to the stairs you can reach the City of Dis before it times out. (Or maybe you have a Homing Phase Device, so even an Invulnerability Sphere that's too far away is usable)

Regardless, the formula from there is simple: set off a nuke in the City of Dis, and use Invulnerability to survive the nuke. Upon successfully doing so, the game informs you that you're very clever, but something EVEN MORE EVIL is out there, and now you can access exit stairs to the next floor; there's one in each corner of the City of Dis.

(Actually, if you get the Trigun you can just use the Angel Arm alt fire and not bother with Invulnerability at all. It's innately a survivable nuking, and does in fact count)

This, incidentally, is the other reason I was saying the Spider Mastermind tends to be a formality. If you're successfully pursuing a Full Victory, you're not going to meaningfully fight her. You're just going to blow up the map without even seeing her. I've actually not fought her very often! It's part of why it's a little frustrating she can't show up in Angel of 100/Archangel of 666!

A couple points of note about all this before advancing toward talking about John Carmack.

First of all, you might expect that you could use a Phase Device or Homing Phase Device to skip to the stairs without bothering with the whole 'nuke while invulnerable' thing. This doesn't work. I'm not entirely sure if the stairs just spawn in or what, but whatever the case, teleportation won't take you out to the stairs before you've blown up the map.

Second, it should be emphasized that nuke timers are time-based, while Invulnerability's timer is action-based. It's entirely possible to set up a nuke, activate the Lava Element, and then die because you ran around a bunch and your movement speed is extremely high, causing you to time out the Invulnerability first. You should either use the period (.) key to pass the time at a fixed speed, or wait until pretty late in the nuke timer's countdown before activating the Lava Element.

Anyway, once you've nuked the Spider Mastermind, it's onward to Hell's Fortress, floor 25, the absolute deepest floor a standard run can ever reach. Hell's Fortress itself is actually very plain: Doomguy starts on the left side of the map, John Carmack on the right side, and the entire map is just... empty of terrain, other enemies, and items. 'ID' is written out in blood, which you'll see as you approach the Mysterious Evil, but this doesn't matter mechanically.

John Carmack himself has unique AI. Initially, he's completely inactive: he won't move from his spot at all until either you get in range to see him, or he takes damage somehow. In the former case, he starts his normal routine, whereas in the latter case he summons the eight Barons of Hell around Doomguy and then launches into his normal routine.

His normal routine is, broadly speaking, the usual AI thing of randomized decision-making, but John Carmack's actual range of options isn't normal.

First of all, he never uses normal movement. If John Carmack wants to change his position, he teleports directly there. This is different from eg Shamblers, which can teleport, but still default to walking places.

Second, as far as I'm aware John Carmack will never perform a melee attack, in spite of having melee stats comparable to the Angel of Death. A related point is he has all those AI flags for using gear and all, but as far as I'm aware he'll never actually do any of that.

Third, he of course has the ability to summon enemies. I don't know what the exact rules of this are, unfortunately, in terms of HP thresholds, rules for how he decides whether to summon or not, etc; I think it's the usual 'roll dice each turn for whether to randomly summon or not', as I've seen him at times summon two or three times in a row and other times taken him out without him ever performing a summoning at all.

John Carmack is also notable for being one of the only enemies in the game who fires projectiles but doesn't care at all about whether other enemies are in the way. Friendly fire incidents can occur in Doom Roguelike in general, of course, but most such cases are accidental friendly fire: splash damage enemies hurting buddies with their correctly-aimed splash, enemies trying to fire on Doomguy but he passes the Dodge check so they aim wrong, enemies failing their Accuracy check and so hitting another enemy on the other side of Doomguy, or occasionally there's a mismatch between what an enemy thinks will happen when it fires and what will actually happen. John Carmack is weird for just shooting right into other enemies, and it's pretty conspicuous since his 'normal' summons always fully surround him.

(He's not unique on this topic, mind: Cyberdemons do this as well. But it doesn't crop up in a standard run since the Tower of Babel's Cyberdemon is completely alone)

Also, he's technically flagged with the 'hunts player precisely' AI, but I'm not sure how much that matters, given how unique his behavior is?

Also, I say he 'fires missiles from beyond Cateye range', and I should clarify this was true even in 0.9.9.7, when Cateye's vision increase was +3. As such, John Carmack is willing to fire from at least 12 tiles away; I'm genuinely not sure what his limit is, and honestly wouldn't be surprised if he doesn't actually have one. (I seem to recall once using a Phase Device to buy time, ending up on the west end of the map, and having a rocket come screaming in even though he hadn't teleported and so should've been way in the east end. But I might be misremembering; this would be from over a decade before I started properly writing these posts)

Overall, John Carmack works out to basically a slightly upstatted Cyberdemon; 50 more HP, 1 more Protection, and that's it if you discount the summons and teleports and so on. As such, if you breezed through the Cyberdemon, you're actually pretty unlikely to have much trouble with John Carmack, especially if you're familiar with his mechanics. I would in fact argue that for a lot of runs he's actually less dangerous than the Spider Mastermind, which feels pretty odd for a secret bonus boss that requires effectively skipping the regular final boss to be able to fight. I'm not criticizing or complaining exactly, as most of the challenge is in the 'puzzle' of figuring out how to reach him and successfully assembling the tools to do so; frankly, usually the peak of difficulty for a run is Limbo/The Mortuary, regardless of whether you fight the Spider Mastermind or go for a full victory, I'm just commenting that it does feel odd.

John Carmack is of course another boss that doesn't show up in Angel of 100/Archangel of 666 runs. As he's a silly secret boss, this makes perfect sense, and honestly he wouldn't even add that much over Cyberdemons already being present. (Even if it is funny to imagine a 'single-monster level' for him) So I don't mind this at all.

Graphically, he got an updated sprite for 0.9.9.8; the one on the left is his old sprite, the one on the right is his new sprite. They're sufficiently similar I wasn't sure I wasn't just imagining a change up until I did a side-by-side comparison, but for one thing the old sprite is blonde while the new sprite is brunette.

Also on the topic of graphics...

... he technically has a unique corpse sprite in the sheet. You can't tell except by comparing the sprites, honestly, and the actual game doesn't use it: killing John Carmack just ends the floor and launches you into the post-game congratulations, score screen, and so on, without ever converting him into a corpse sprite.

Overall, John Carmack is a cute little easter egg/final boss fight, though I do wish some aspects of the whole thing were tweaked. It's a little disappointing how, once you know about full victories, the intended play experience becomes 'never fight the Spider Mastermind, ever', and while John Carmack can be a bit intimidating the first few times you fight him (8 Barons appearing out of nowhere? Yikes!), in practice he's not difficult or... terribly interesting to fight. Just a quick victory lap. It'd be nice if he was a bit more engaging.

Ah well. With updates resuming, maybe such will happen?

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Next time, we cover another very special boss.

See you then.