#3iac post mortem

[charlievermin]

Three Is A Crowd: post-mortem level analysis

At last, I've gotten around to gathering together my Doomworld Megawad Club posts and publishing them in one place! Here's all of them at once.

And on the second anniversary, 3IAC might come to life again...

[charlievermin]

MAP30: Extinction Burst

This was the third map I made, alongside with the hellish area also partially featured on MAP06, MAP09, MAP28 and MAP29. In this one, the original protagonist finally gets released from the cage, and sets out to avenge the one who just set him free in his final moments.

It's a really unusual map, linear and fragmented. Semi-reasonable challenges alternate with a few ridiculously unfair ones that throw you into rooms full of monsters with no cover and require foreknowledge. Fortunately, the level's pacing keeps trial and error from being too painful. Once again, evoking a particular mood took priority over conventionally attractive gameplay. As its plans backfire, the powerful being you're fighting against loses its cool, and uses the same teleport attack as it did against your friend to fling you into a number of unfair traps - such as a room with eight arch-viles and no cover whatsoever, for instance. But you still prevail, through sheer determination... with a sprinkle of time-bending powers, perhaps.

It begins with a pistol start once more, but this time you regain your gear very quickly - some of it you kept in your cage the entire time, some more, alongside the fateful yellow skull, taken from your fallen comrade, and the chaingun from the teleport hub your comrade originally came through, where a little skirmish between imps and chaingunner zombies apparently took place while your comrade was busy suffering through the trials of MAP29. That entrance from the playable area of MAP28 is an interesting one, but I didn't think of mentioning it before. While 3IAC as a whole cares little about realism, it has a whole bunch of worldbuilding bits here and there, even in Hell. MAP05 has a little conveyor belt with hanging bodies and lava, and you can see it extend beyond the playable area through a pipe made of midtextures. MAP28/MAP30 has this room that looks like a teleport hub, seemingly allowing demons from all corners of hell to come and speak with their leader.

On to the actual map, the first trap you get thrown into as you try to ascend the stairs is one of the unfair ones, with enemies from every side and no cover. My preferred strategy for this one is to fire the SSG immediately after teleporting, before you can even move or see anything. This clears out some of the demons in front of you, freeing up a bit of precious maneuvering space. And since it's meant to be a death trap, just making it hard to survive wasn't enough. It also has no apparent exit at all, but of course it doesn't take our hero too long to locate the hidden passage, probably built for the demons themselves.

Next up is a little less chaotic obstacle, inside a quasi-outdoors area just like on MAP29. The bars that drop down suddenly don't do much to hamper your ability to grab the invulnerability, but it's the thought that counts. After that comes the ultimate unfair trap, eight archviles with no cover and no hope unless you still have the invulnerability left over after treating it as a very expensive radsuit. And of course it has no obvious exit again. Neither does the area after that, which is a different style of quasi-outdoors (also used by MAP29 before), and is much more forgiving thanks to spider masterminds being spider mansterminds. Let's just pretend that making them infight was a feat of ingenuity on our hero's part.

And finally, there's the part with barrels. Believe it or not, the intended way to survive this one is actually to grab the armor, let the barrels in the back get crushed, and then race the chain reaction to the teleporter, killing the monsters along the way and trying not to set off any more explosions along the way. And I did it, many times. Then I discovered that thing with shooting the barrels behind the crusher and running towards them. I really would've patched that out, and forced you all to race the barrels, if it wasn't for the fact that not letting the player take advantage of the designer's oversight would go against the entire concept behind this level.

One of the fun things about this map is that all the wild teleporting gave me an excuse to incorporate a lot of different themes. Every place you get thrown into looks different - first the gritty brown dungeon, then the bright burning yellow rocky valley, followed by a borderline techbasey room, then some vine-covered green brick exterior, and finally a fancy wooden mansion. I didn't have any custom textures yet when I was making this map, and so the long corridor has a bunch of weird lava cubes to serve as ceiling lights.

It all culminates in a scene that closely parallels the title screen: you find yourself in a gray orthagonal maze, with a giant goat-headed monster looming above it all and trying to stop you from making it out alive. I didn't think of that parallel when I designed it, or at least not consciously, but it's really cool that it's there.

[charlievermin]

MAP29: Sheer Poison

The 9th map, and yet another one with an extra intense and unrelenting gimmick. In this one, you're taking damage. Non stop. Unless you're standing in water, but there's almost no water, so that doesn't help much. The water thing was mostly just to easily make secret sectors, really. You just gotta run, collect health, and run some more. It was hard to predict how this one was going to feel for other players, cause when every step you take hurts, knowing the layout beforehand makes a REALLY big difference. That's why I decided to be pretty forgiving and health stuff is all over the place. That should give you a chance to survive as you try to find your way through the not entirely linear level. I mean, you have to press a fairly inconspicuous switch just to escape the first area.

The ending is similarly non-obvious. You have to find a secret wall with a switch behind it, which temporarily uncovers another switch, which after being pressed enough times can let you reach the way out. Maybe it will be slightly easier now that I added a very similar looking lift pillar on MAP05... if anyone remembers that after 24 maps, that is. Either way, it doesn't feel straightforward at all, and that's for the narrative first and foremost. This level is supposed to be the protagonist's inescapable punishment brought upon him by the big demon in charge, and similarly to MAP08 it tries to evoke the feeling that you're not meant to succeed. 

Firs, the hero gets tricked with a fake techbase. This bit (right at the start, appropriately enough) might be the most unforgiving - the health is scarce, you have little in the way of armor, and then there's also a whole bunch of hitscanners ruining your day, taking advantage of your initial lack of weapons. The room is confusing even despite its tiny size, forcing you to jump over some crates just to get to the exit. And when you do, the facade melts away and you find yourself in a hellish cave with no exit.

The lack of exit, of course, is greatly exaggerated. One of the skulls on the wooden boxes is a noticeable switch, which opens a nearby wall. Not very hidden, but certainly not the most obvious either. Past that, you reach a somewhat more spacious location. With a lift on the other side of the canyon not yet ready, you can either jump in and find the secret on the far side, or follow another tunnel to the castle. With the last three maps still having the city sky enforced by vanilla doom, I had to resort to tricks if I wanted to create the impression of hellish outdoors - and after MAP28, I opted for more artistic solutions, instead of technical ones. In this case, the castle area simply happens to be brightly lit, and topped by the one and only, glorious CEIL4_1 - the ultimate dark sky substitute, utilized even by Romero in Sigil. The castle area has a whole bunch of different paths - you can take the very literal path or follow the trail of medikits and stimpacks, you can take a detour to grab some cell ammo, you can approach the staircase from the front, or from the back if you fancy an extra berserk. I love rushing up those stairs, letting the imp at the top stop me from overshooting, and rewarding them with a super-accelerated fist to the face. Up there, you can simply drop down, or maneuver your way to the plasma gun first, or jump further to get the invulnerability secret, or even run across the entire castle wall until you reach a teleporter that skips you all the way to the other side of the lift. The last part is so secret, it doesn't even count as a secret.

On the other side of the ravine, there's more paths to take. You can either go through one of the two obvious doors, or take a sidepath to grab a blue armor, and blow up a bunch of zombies early. The right door leads to a shotgun you can pickpocket from a revenant, inside a really cool-looking room with a bunch of cages and corpses. I really love the way it turned out, and it's one of the few things that make me wish the player wasn't forced to run everywhere. Maybe I'll reuse that design in another wad somewhere. I kinda did in MAP05's backpack secret, but that variant was not quite as good.

Anyway, the left door is the way forward, and it leads to you a fiery courtyard that contains another creative replacement for the sky - bright FIRELAVA walls above the regular bricks, topped with a blood ceiling. It goes great together,  and looks considerably more 3D than either of the two alone. The courtyard also comes with another selection of paths. Two of them converge soon after to lead further into the level, and require both the red and blue skull either way. A shorter tunnel on the opposite side only requires one key (either red or blue), and lets you lower the central pillar with the megaarmor and the hell knight/revenant/arch-vile (depending on skill level). Finally, there's two paths that let you obtain the two keys needed. The blue key path contains a little taste of The Chasm, with the walkway actually getting progressively thinner as you walk alongside it. It also contains the wad's only instance of a secret hidden behind a waterfall. The red key path contains crushers... as well as something else.

It starts with a chain of secrets, that's inspired by wolf3d more than anything. The wolf3d engine doesn't offer many options when it comes to designing secrets, and one common way to spice it up was secrets inside secrets. Inside secrets. I loved that as a kid, and I still do. my favorite bit was in E2L3, in which you keep opening secrets with more and more valuable riches inside, culminating in a few 1ups. If that's still not enough for you, you get treated to a crowd of soldiers pouring out on you, as if to punish you for your greed. I already implemented this once in this megawad, in the yellow key area of MAP17, where you can open a series of closets with a medikit, shells, rockets, and finally a chaingunner. That one is a double subversion though, as you can get the blue armor after that. On MAP29, though...

This whole secret was the last thing I added to this map, after the megawad's initial release actually. MAP29's name is obviously a reference to yakfak's map of the same name, but then I thought that aside from the love/hate factor, my map doesn't really live up to its namesake. And so I decided I should add at least one big, dangerous and unnecessary secret area.

So you open up a wall to reveal a stimpack, and that in turn may lead you to open up more walls after that one. You find a medikit, then a soulsphere, and then what? The answer is: a one-way dropoff, and a bunch of radsuits. It's time to make a run through a long branching tunnel that encircles nearly the entire map.

To begin with, you pass a bunch of pillars, with one stimpack to the side of each of them. You may want to memorize their positioning if you want to avoid some nasty surprises along the way.

Surprise number one - a boring old fork in the road, with the wrong path terminating quickly.

Surprise number two - a mundane fork again, but this time the wrong path goes on for a little longer before you get to realize you've wasted your time.

Surprise number three - this time, the wrong path ends with a little loop to confuse you.

Surprise number four - the wrong path goes back to wrong path number three, through a fake wall.

Surprise number five - this one's less confusing but still plenty time-wasting, as you get mocked with a barred pathway.

Surprise number six - this one's real interesting. Two dark paths, both of which seem equally valid... until you take the wrong one, and get set back all the way to the castle at the other end of the ravine. Hope you left a few medikits over there!

Surprise number seven - the grand finale, starting with another dropoff, but this time you get the see the bars from the start... guess what. The bars are intangible, and the seemingly better path has an invisible wall. The only way out of that is through a fake wall, and an entire maze to get through on the other side. I also reused the maze as a deathmatch arena initially, which turned out to be... a terrible idea? Well, not really I'd say. But still less than ideal.

After all those forks, there's still a long bit of path that squeezes the last bits of durability from your radsuit before you reach one of the very few areas of the level free from constant pain. Your reward is three medikits, three cellpacks, a computer area map... and a tantalizing view of a radsuit that could actually help you with the level proper. Then it's back to the grind...

So you got both of those keys, destroyed the zombies on the other side, and what to you get? A tantalizing view of a hole labeled "EXIT", and a maze. At least there's a radsuit secret nearby… though my daring beta-tester Joe Ilya had to suffer without it. The maze is short, but it does its best to mess with you - forcing you to go inside and then outside of the metal walls, making you pass by a grate that looks just like a dead end… well, eventually you can make it through and drop in. You drop in, land in a wet hole, and it no longer hurts. Congratulations, you win.

What? That's not a happy enough ending for you? Fine, have it your way. You can press the exit sign to lower a chunk of the floor. The pain is back as soon as you step forward, and after the eerie silence of the maze you're greeted with more demons to kill or be killed by, again. At least this time, there's plenty of health, ammo and armor to assist you, and after painstakingly waiting for some stairs to raise, you finally get to reach the good old exit door, and press a switch behind it.

No, wait, that's not it. What happens is the floor collapses under you, you hear a demonic greeting, and you get looped back to the beginning of the big room, as it gets refilled with demons all the while. Enjoy your eternity.

Alternatively, you may find the secret switch that lets you raise a certain lift (much like the one on MAP05), and keep pressing it until it's raised high enough to let you slip away. At last... you have escaped the grasp of your oppressor, and got to save your loved one. Too bad you're running on fumes at this point...

. . .

As you can see from this wall of text, I've put a whole lot of thought into this map. Most of 3IAC's maps is just a bunch of good old demon-shooting action with gimmicks sprinkled here and there, but this? This is a whole experience. With an intense-ass narrative I wouldn't compromise on for gameplay's sake. And same goes for MAP30, but at least that one's both shorter and more linear, so you may find it more bearable.

[charlievermin]

MAP28: Reunion

The fourth map I made. Like all of the maps from 27 onwards, it contains an essential piece of storytelling, but it's not that notable otherwise. My favorite part of the map might be the temporary staircases that form to let you out of the gray rock areas accessed by teleporters. Another fun gimmick this map used to have was keys on top of sprite pillars (like the soulsphere in MAP23, and a few different objects in my DMP2018 map), but for some reason just one of them kept glitching out and warping the column sprite on top of the actual, invisible sector pillar, despite being identical to all the other columns.

The hellish sky at the start (mirroring the other hellish arrival at MAP02) is my favorite kind of trick - the kind that's bafflingly straightforward at its core. It still required some finesse, with the sector with the sky linedefs being fullbright, and non-orthagonal to avoid fake contrast. By the way, the two secret tunnels on MAP22 also have some linedefs around them with a vertex shifted just one unit away from being orthagonal, to once again turn off the fake contrast that would've made the tunnels to easy to see. In the end, the sky hole ended up looking ever so slightly imperfect from the bottom… but it's hell, so I have an excuse for any and all illogical visuals.

The anniversary edition reworks the main area a fair amount, replacing many of the identical pillars with transparent cages, each with a different floor which might help you orient yourself in this otherwise extremely symmetrical arena. As you progress, some of the other pillars rise up and eventually turn into crushers as well. That's got to spice up the later parts of the level! And also deathmatch. This was the very first deathmatch arena I made for 3IAC, only to find out that it actually kinda sucks. Well, no more.

On the other hand, the beginning was way too extreme compared to the more beatable follow-up, so I smoothed it out with a soulsphere and an invulnerability you can grab at your leisure.

[charlievermin]

MAP26: Unlikely Ally

The 13th map I made, the first proper city map, and the subject of the third challenge: "Make the player feel sorry for an enemy". Oh boy! Talk about a vague objective. How am I supposed to control the player's feelings?! Some people feel sorry for the demons by default, no special setup needed. Others will see a helpless pinky stuck between twenty barrels and feel nothing but righteous satisfaction.

Finally, I decided on something ambitious: I would make a demon meet a sad predicament, but before that, I would PROVE to the player that the demon was not, in fact, out for their blood. And that brings us to the level's current setup: you meet a caged imp (It's actually possible to kill him at that point if you try REALLY hard, but what matters is that an itchy trigger finger alone isn't gonna do it), and later on you jump into a thin corridor. As you go though it, a wall opens up and an explosion begins to approach you… the one switch within your reach doesn't save you… but it does release the imp! And the imp does not reward your selfless action with a fireball to the face. No, it takes a look at you, and then presses a switch to open up a closet and let you hide from the barrels.

Okay, what? Let's back up a little. What's even going on?! I thought this was vanilla Doom, I hear you say. What's with the friendly monsters pressing switches?! Well. With enough knowledge and stubbornness, everything is possible.

I always liked the idea of the player not being the only one to press switches. And I actually implemented that in my Doomworld Mega Project 2018 submission, where you can see a Nazi throw a switch behind a bulletproof window in the prison area. But that was just a motionless guy staring at a wall that changed, and in Boom format on top of that. This imp actually walks up to the switch, and only then is the switch pressed. In vanilla. So how does it work? There are many components.

First of all, there's the bulletproof window. It's a real classic, so I won't elaborate too much on it. Just an untextured raised sector, mostly. What matters is that it keeps the imp from attacking you, and vice versa. But since the imp has been alerted (you probably fired your gun in the vicinity already, and if you didn't, you BETTER do now!), it will still try to chase you down. How on Earth does that translate to going AWAY from you, and towards the switch? The answer lies in monster AI! Monsters usually try to go towards you, but they'll try other directions if they have to. Curiously enough, there's one thing all monsters hate: making 180 degree turns. They are capable of it, but will only EVER do it if it's literally the only option they have besides not moving at all. If they can move without making a 180 degree turn, that's what they'll choose to do, even if they have to stray far away from you as a result. You can easily see this in E3M1 of Doom: once a demon begins walking back through that thin corridor, it won't turn until it bumps into a wall at the the end, as that's when the 180 degree turn becomes a necessity. And so, I put up a few monster blocking lines, close enough to each other that the imp cannot move sideways at all. And so it will walk in a straight path between you and the switch, only turning upon reaching the end as that's when the 180 turn becomes unavoidable.

Okay, so he approached the switch. What then? Vanilla Doom doesn't have many monster-activated linedef actions. It's just one type of door, a few kinds of teleports... and, crucially, walk-over lifts. In original Doom, that usually just means that thing where a lift goes down as soon as you step on or off it. But that's a remote action! It affects whatever sector is tagged. And that opens a whole lot of possibilities. For starters, the door of the closet that lets you hide from the barrels is obviously a lift. But so is the switch itself! The way it works is just like in my DMP2018 level: there's a super thin sector in front of the switch face, with the switch off texture. Behind the thin sector, there's a switch on texture. And when it's time for the switch to activate, the tiny sector gets lower. And that's it! Only in this circumstance, I didn't have the option to insta-lower it, so instead I just made the texture lower unpegged. That makes the switch texture change gradually, but a lift movement is fast enough to keep it from being too noticeable! To this particular switch, I added an extra touch: ANOTHER extra thin sector in front of it, this one working as a regular switch and preventing the fake switch animation thingy from happening right in front of the player, when it would be a lot more noticeable. That outermost sector is only raised if the player can get close, and gets lowered for the duration of the "switch-pressing imp saving you from barrels" sequence.

The other encounters with the imp largely rely on the same mechanics: remote lifts and tight spaces forcing the AI to behave in the desired way. There are also a few lifts or otherwise moving floors that sink down and form tiny invisible gaps in the floor, dynamically restricting the monster movement. After all, monsters never step over tall dropoffs... even if the gap is so thin it's not even possible to fall inside at all. This has been another hugely important part of this. For example, the imp just goes back and forth at first, but as you continue onward, one of those floors raises and lets the imp go, teleporting him to the next section.

Finally, the imp "picks up" a keycard and brings it to you. It just gets lifted high up (using this mechanic where items start off on whatever height their center is, but then snap back to the highest floor within their hitbox as soon as any sector movement at all occurs inside said hitbox), and then another key pops up (using the same mechanic) elsewhere.

Then finally, the feeling bad part comes in. It's not very tech fancy now, just a static scene of an imp dead in front of a baron. It used to be just as quirky, advanced and animated as the rest of scenes, with the baron very intently killing the imp right in front of your eyes, but it ultimately proved too hard to implement elegantly, or even consistently. It was gonna use the same trick as Batman Doom, which features two gangs fighting each other without your involvement at one point. Only in Batman Doom, they had Dehacked that could force the two groups to shoot as soon as they're alerted, and aggro each other immediately. Here, I could only rely on RNG making the imp hit the baron sooner than later. And even then, the baron had to enter the pain state to react at all! I made another convoluted contraption full of monster-activated lifts... but even in the best case scenario, it still involved the player sitting in a hole for a long while, waiting for the two monsters to do their thing. It was a pretty neat effect still, but I think I never managed to make it 100% reliable, and that's why I gave up on it in the end.

Miscellaneous notes:

I'm pretty sure this level has the only instance of brown slime in the whole megawad, and it has a nice realistic touch of a flooded staircase.

The hedge looks messed up when used on a lower texture in vanilla... luckily, the particular texture being used makes it look alright!

I love the combination of the strobe light behind a lowering wall in the red key area. It feels kinda intense and foreboding, like something's about to happen, and it does.

To avoid confusion, your unlikely ally is the only imp on the whole level. Let me tell you, making maps without those guys is something of a challenge! They're the most versatile Doom monster, hands down.

The starting area is one of my favorite places in the whole megawad. I just managed to get it looking particularly lively and realistic...

[charlievermin]

MAP25: Perturbator

There are many maps in 3iac I'm proud of, but this one is my favorite in terms of aesthetics. It feels unique, and everything works together really well. Even the blinking light in the main room syncs up with the beat of the music. I'm less confident about the gameplay (the bold choice of immediately giving the player a plasma gun with 300 cells on MAP19 made all the subsequent maps tricky to balance…), but it seems I managed to work it out well enough.

The map was primarily inspired by Club Doom (I even added the Williams Entertainment logo in homage), but ended up only mildly similar. I also listened to Hotline Miami OST while designing this level, and named it after one of its composers.

As different as it is from everything else there, the starting area is actually my favorite bit of the map. It's just a tiny cramped pathway between a building wall and a fence, but I made sure to cram a lot of detail everywhere the player can see from their point of view, and now it feels like a huge thriving city all around you. Just don't noclip to check.

The exit has another instance of unusually seamless transition: instead of a switch in an empty room, the exit area is more of an airlock type thing, and the textures correspond to the beginning of MAP26. 

[charlievermin]

MAP24: Dirty Dealings

Challenge: You must approximate the feel of a store with a storekeeper from which you can buy things... but maybe the store turns out to be EVIL?!

Fresh after completing the MAP26 challenge, I honestly considered putting together some kind of crazy contraption made of conditionally lowering floors and monster-triggered lifts that would have implemented a system of spendable currency into a Doom level. But eventually, I settled for something more down to earth, and had the player exchange keys for weapons from a very friendly Archvile, who runs a cute little shop with their face on the front.

I think I was initially planning to make all three exits real, requiring you to only take two of the three paths to finish. That would've been pretty unique, but for some reason I decided to make all of them fake exits instead. Maybe I just really wanted the player to fall for the BFG trap, which requires all three of the keys and satisfies the second part of this map's challenge.

Here's some other interesting things about this map:

The tiny central building you start in has a subtle 3d effect going on. There's a small tunnel underneath it containing some armor, and it has a fully solid ceiling, but there's also a room visible right above it. It works pretty much exactly the same way as the MAP23 tunnel, except the upper area is always above you so I didn't have to obscure the view with anything. I just had to make sure you can't see the tunnel's ceiling and the upper area at the same time, which is made easier thanks to Doomguy's stiff neck.

This level is the first one to prominently feature bulletproof glass. It already exists on MAP23, but only in one small decorative area you wouldn't want to shoot at anyway. Still, I made sure to make it all properly impenetrable! Now I wish I used it some more. I'm sure it could've had some good uses in the techbase.

The spooky gargoyle jumpscare from MAP10 finally makes a comeback! And this time, it actually unleashes a horde of demons.

Each of the fake exits is fake in a different way. The eastern one is just a door that leads to nowhere, the western one springs a trap when you press a switch (I really like the weird little texture I applied to the newly exposed door edge after the walls disappear), and the southern one doesn't let you press the switch cause it teleports from one wall to the other when you try to approach it. You can guess which concept is my favorite.

I've been looking for an excuse to implement that western room puzzle for a while. So Doom has those "raise to next higher floor" actions and such, sure. And sometimes what counts as "higher" or "lower" can change over time! That's really interesting too. But the real interesting thing is, that height also gradually changes over time as the floor is in motion! I feel like there's a lot of puzzle potential within this, and my little make-your-own-staircase design is just a tip of the iceberg.

[charlievermin]

MAP23: Quartered

I think this one was the last city map I made. It started some time ago, as just two things: the big gray arch… and the 3d tunnel between two buildings. I really like how that one worked out, too. It's just an untextured lowered ceiling, one unit apart from the walls to prevent HOMs, and the hole in the ground is obscured from above with a fence on one side and crates on the other. I used the same trick for the MAP20's megaarmor secret, except that one uses less sectors and just has the ceiling one unit above the surrounding floors, which makes it look a little imperfect.

The whole thing has a nice semi-hellish vibe, especially with the weird funnel-shaped middle point, and I really like the gameplay and non-linear progression in this map. I end up tackling the areas in a different order almost every time I play.

Also, these fake elevator doors are pretty sweet too. I unlocked some hidden potential of DOORSTOP there.