The Stack

By now, I seem to have pretty much left the City behind. The story has taken me to the forgotten spaces below the city, home to the Stone Giants.

Stone giants are what would be called “Large” in Dungeons & Dragons. That is, they have a 2×2 footprint. Although they look more threatening this way, the larger size doesn’t make them more more powerful or even let them move faster. Quite the reverse: it limits their mobility. There are puzzles to be made from this weakness, by forcing the player to either take advantage of it (ducking into narrow tunnels to escape them), or overcome it (herding them through difficult passages). When hurt, stone giants break apart into four one-tile stone golems (a familiar monster from JtRH), leading me to suspect that they’re made of the same kind of rock as seen in Asteroids. Golems collapse into impassible rock when slain. Since obstacles of this sort are the giants’ greatest weakness, it’s like the giants carry within themselves the seeds of their own downfall. (Much like the Rooted Empire itself, it seems. There’s some kind of parable about hubris and data storage going on back in the story. More about that later, probably.)

The reason I’m taking the time to write about the giants in particular is that this is the first new creature shape in The City Beneath. The original DROD had three shapes. You had your standard one-tile creatures, such as roaches, goblins, wraithwings, and evil eyes. You had tar, which formed amorphous multi-tile blobs, at least two tiles thick in all places. And you had serpents: one tile wide, arbitrarily long, moving in right-angle wiggles like in the classic Worm. Journey to Rooted Hold introduced several new monsters, including new kinds of serpent and tarstuff, but added only one more shape: standard-plus-weapon, a shape used for armed guards and the Slayer. In a sense, even that wasn’t really a new shape, because that’s Beethro’s shape.

Well, The City Beneath gave us another new serpent and another new tarstuff, but only at this rather late stage of the game do we start seeing giants. I wonder why? Perhaps the designers felt that the stone giants had limited potential for reuse. Or maybe not; if you’re introducing a new element on nearly every level, something has to come in near the end.

I don’t think I’ve adequately described the experience of solving a DROD room. There are essentially two modes of thought involved, which we may as well call “strategic” and “tactical”. The difference is that tactical thought involves using the “undo” feature repeatedly, whereas strategic thought involves “restart room”. Some rooms emphasize one, some emphasize the other. I recently encountered a room in the Pirate Hideout level that seems good for illustrating both modes and the interplay between them. The solution to this room is given away in some detail below.

Basiclly, what we have here is a simple, wide-corridored maze sprinked with Roach Queens. The Roach Queens are held immobile in little chambers lined with one-way force arrows. The roaches spawned by the queens can get out of the chambers, but you can’t get in to kill the queens until you open a way in. All of the chambers have gates that are color-coded red, which means that they’ll only open after you’ve collapsed all of the trap doors in the room. The trap doors (which show as pink floor tiles in the screenshot above) are scattered throughout the maze. In addition, there’s a Brain in a small area that you can only exit through a green gate, which will open when all of the monsters are dead; this means that you have to kill the brain last. Understanding this gives you a series of strategic goals: go through every part of the maze stepping on trap doors, then go through it again killing roach queens, then kill the brain. This much, you could plausibly figure out just by looking at the level layout (although in practice there are always details that escape my attention until their importance is forced on me during play).

So far, so easy. The difficulty comes in when you actually have to navigate the maze, with roaches coming at you from all directions, guided by the brain. Remember, your sword only points in one direction at a time, and you can only swing it in a 1/8 arc per turn. So surviving involves tactics such as taking advantage of the walls for cover, going after small groups of roaches first in order to have fewer directions to watch, and maneuvering to kill one roach every turn whenever possible, lest they grow too numerous and choke the hallways.

In fact, it soon becomes clear that the queens in this room are generating roaches faster than you can kill them, and that to survive long, you need an extra edge. This is provided by speed potions. Introduced earlier in this level, speed potions are the level’s theme and the key to all of its rooms. They act pretty much like the speed potions in Nethack, allowing you to move at double speed until you leave the room. There are two in this room, but neither is easy to reach without getting killed. So, tactical concerns introduce a new strategic goal: get one of the speed potions before doing anything else. Once you’ve got the potion, you have to discover new tactics that take advantage of it. You still have to kill the roaches as efficiently as you can to avoid being overwhelmed, and a lot of the habits of defensive swordsmanship are no longer necessary. Given the right timing, you can defend a three-tile-wide hallway without retreating, or charge into a pair of roaches side by side, rather than spending a turn blocking one with your sword to separate them.

Now, it took me a while to notice this, but one of the two speed potions in the room, the one harder to reach, is not optional. You have to walk over it in order to reach one of the trap doors, and walking over a potion automatically applies it. I had naturally been going for the easier-to-reach potion first up to this point. What happens when you drink two speed potions? This was the first room to contain two, so I didn’t know. It turns out that they cancel out, reducing you to your original speed. This is disastrous. My first thought was that if I saved that trapdoor for last, I could immediately start killing queens, reducing the roach influx to something I could manage without the extra speed. This failed: you can kill at most one queen before getting killed. So I tried another approach: restarting from scratch and going for the hard-to-reach potion first. This took some tricky footwork, and I wasn’t really convinced that it was possible, but I did finally manage it, and was fairly confident that I had cracked the puzzle.

Once you start killing the queens, it’s all mopping up. The tactical concerns become gradually easier as roaches are produced in smaller numbers. After giving the screen a final look-over to make sure that I haven’t missed anything, I plunged my sword into the brain, and Beethro gave a hearty chuckle, a signal that the room was solved.

I keep returning to the question of how to play games for optimal enjoyment. Is it better to play in a single obsessive weekend-consuming burst, or spread it out into smaller sessions? I’ve become convinced that the latter is better for RPGs, which become tiresome when played too long. For puzzle games, I’m not so sure which approach is actually better, but I do know that I always want to play them in obsessive burst mode. I played through the first two DROD games that way. But there are demands on my time just now, and I haven’t had a weekend to devote to The City Beneath.

In fact, I’m going to have to put it aside for a week. I’m going to be out of town, without access to the computer I’ve been playing it on. May the anticipation of returning to it make it sweeter. I’ll try to do some posts during the week all the same, but probably not about DROD.

For what it’s worth, I think I’m more than halfway through the game by now, as I’m well past the second of the city’s three great gates. (The first is at the very beginning. It’s not clear to me yet how much content there is after the third.) The story has returned me to the surface for the second time, and I have just started encountering the mysterious Gel, a previously unseen tar variant.

Journey to Rooted Hold introduced a recurring antagonist: the Slayer. Slayers are kind of like the Terminator: perfect killers, relentless and unstoppable, something to be escaped from rather than defeated, at least until a climactic confrontation with a lot of pyrotechnics. They’re created to deal with nosy delvers like Beethro who threaten the security of the Empire. One starts pursuing him early in the game, and keeps on appearing every so often right up to the end.

The key thing about the Slayers is that they’re always armed with a vicious hook that has the same reach as Beethro’s Really Big Sword, and they always points it towards Beethro. This means it’s absolutely impossible to kill them directly.

Now, The City Beneath has Slayers. They’re even important to the overall plot. But this time around, they’re not so hard to kill. The game’s excuse for this is that the ones attacking you now aren’t full Slayers yet, but Slayer trainees. Their hope is that if they kill you they’ll be allowed to fill the vacancy left by the death of the Slayer from Journey to Rooted Hold.

The interesting thing is that the trainees don’t seem to be governed by a different algorithm than the full Slayers. The only reason they’re easier to kill is that they show up in rooms where the terrain is against them. The most extreme example appears in a room containing lots of hot tiles. Hot tiles are new in TCB. Anything (be it monster or Beethro) that stays on a hot tile for more than a turn burns up. Hot tiles are an especially stupid place for Slayers to be, because they’re always pausing in their pursuit to reorient their hook or send a wisp to find a path to Beethro. (These pauses are the basic weakness that allowed Beethro to repeatedly escape from the Slayer in JtRH.)

Eventually, Beethro has to apply for a job in order to be allowed deeper into the city. He applies for the job of Slayer, because he knows there’s a vacancy, and because it’s really the only thing he’s qualified for. To get the job, he has to defeat five other Slayer candidates at once. This is one of those staggering moments — five at once! We spent an entire game fighting one. But it turns out that five Slayers aren’t that much harder to defeat than one, owing to the fact that they all act pretty much the same. If they were smart enough to coordinate their attacks, they would be formidable, but they don’t. Herding them all to the same place at once is a little tricky, but really just requires persistence, not cleverness.

Not long after this, Beethro has to kill 255 Slayers at once. Not quite through the same means, though.

I’ve come to really like the improvements that have been made to the DROD user interface. Basically, each episode makes more information available.

For example, one of the basic mechanisms in DROD is orbs that open, close, or toggle gates when struck. The City Beneath also has pressure plates that do the same when trod on (which means you can trigger them from a distance by inducing monsters to walk over them). But the orbs and pressure plates are not necessarily near the gates they affect. In the original DROD, if there were multiple orbs in a room, the only way to know what they did was to try them out, which you could only do for the ones that are acessible at any moment.

Well, ever since Journey to Rooted Hold, you can click on these controls to highlight the doors they affect, in colors indicating whether it opens, closes, or toggles each door. I didn’t use this feature much when I learned about it, but it’s become a very big deal. One of the basic DROD room patterns is making the player hit a series of checkpoints in a specific order by giving each an orb that unlocks the door to the next. With the new UI, I can know in advance the order I’ll have to hit them in, and plan accordingly. Even in rooms where all the orbs are accessible from the beginning, it’s nice to not have to try them all out (and possibly render the puzzle unsolvable in the process because you let the cockroaches out too early or something).

Once they implemented this click-to-highlight system, the designers started using it in various other ways, such as clicking on an Evil Eye to show its line of sight, or (new in The City Beneath) clicking on a bomb to highlight the area that will be affected by its blast. This was never secret information. All bombs in the game have the same blast radius. So displaying that radius on demand is just a convenience. You know something? Conveniences are nice.

I actually didn’t notice most of these features in Journey to Rooted Hold, which wasn’t as aggressive about pointing them out as the new episode, but there was one enhancement that was hard to not notice: it added a clock to the screen whenever there was a timed event pending. Mainly this meant timing the spawn cycle of Roach Queens and Tar Mothers, both of which cause new stuff to appear every 30 turns. Knowing exaclty how soon that’s going to happen is often crucial, and it was easy to lose track when playing the original DROD.

The general principle here is that providing easy access to crucial information helps the player, by making the process of solving the puzzles easier, but doesn’t actually make the puzzle itself easier. A subtle distinction, perhaps, but an important one, and one that’s illuminated by my recent experiences with Roberta Williams’ Time Zone. Williams chose to make things inconvenient for the player, making you reload saves and do things over again because you used the wrong weapon or brought the wrong selection of objects into the endgame. She chose this, I think, because she was trying to create a difficult game, and the understanding of the time did not differentiate between difficulty in solving a game and difficulty in playing it.

The designers of DROD have a better idea of what their gameplay is about. It’s not about keeping secrets from the player. It’s about applying known rules in complex and novel ways.

It’s interesting, then, that they still choose to retain the possibility of hiding information in some ways. Let me explain: I’ve just reached the point in The City Beneath where the Living Tar makes its appearance. Living Tar, and its variant Awakened Mud, form DROD‘s version of ooze monsters. In its simplest state, tarstuff (the word applies to both forms) lies in inert pools covering multiple tiles, not crossable and only partially vulnerable to attack: Tar is invlunerable on its convex corners, while Mud is invulnerable everywhere but its corners. Either must be cleared away one tile at a time.

Now, until cleared, tarstuff conceals any terrain features in the tiles it occupies, including orbs, pressure plates, gates, and even walls. This is significant information-hiding. The original King Dugan’s Dungeon had some puzzles that relied on tarstuff’s concealing properties. For example, there was a maze completely covered in tar, which you had to cut carefully lest you wind up with an invulnerable tar corner blocking the path you needed to take. This isn’t really in the DROD style as I’ve described it above, but it’s typical for the first game in a series to have a few klunkers.

The City Beneath provides a way to see what’s under tarstuff, but it isn’t a user-interface feature like the other things I’ve been describing. Rather, there’s an in-game “token”, a special tile type that effectively gives Beethro X-ray vision when activated, rendering all tarstuff translucent.

I can think of three possible reasons why tarstuff visibility isn’t handled through a simple click like the other new information features. First, it could be that there will at some later point be puzzles that rely on concealing information with tarstuff. I hope this isn’t the case, because it’s difficult to imagine the result being anything more than a guessing-game, and I think the DROD designers are past that now. Second, it could be that the designers wanted to preserve the ability to play levels created in the older engines without drastically altering the play experience. I don’t know that that’s a great priority for them, though: surely some of those old levels are drastically altered by the ability to click on an orb to see what it does. Third, it could just be the difficulty of creating a user interface to deal with it reasonably. If you click on tarstuff to see under it, and you click on orbs to see what they affect, how do you see what’s affected by an orb concealed by tarstuff?

Let’s make one thing clear: DROD is fundamentally a bag of puzzle-rooms. It’s got aspects of narrative and world-building, but they exist as a frame for the puzzles, and are wholly subordinate to them — for example, the gameworld is full of gates that only open after all the monsters in the room have been killed, even in areas that aren’t in dungeons. This makes no sense in the world or the story, but the game trumps them both. Still, the story isn’t just appended to the game (in this episode, anyway). The story complements the game, providing a rationale for game elements.

For example, I’ve just been through a part where Beethro briefly returns to the kingdom of Dugandy. Through the machinations of the Empire’s agents, Beethro is a wanted man, a suspected traitor to his own king. So, sneaking into a guardhouse (a rare stealth segment — Beethro doesn’t want to kill his own countrymen), he steals a guard’s uniform to use as a disguise. It turns out to be a very successful disguise indeed: while he has it on, the monsters in the dungeons won’t attack him first. Once Beethro makes an attack, everything charges. This temporary change to the basic rules of the game is the basis for a set of puzzle rooms, ones that can only be solved by not initiating combat immediately.

Was the puzzle sequence inspired by the story, or was the story invented as an explanation for the puzzles? Probably a little of both, but the game gets more out of it than the story does.

On a smaller scale, though, narrative influences puzzle content all the time. I remember reading an essay by one of the designers, giving advice on how to make homebrew DROD levels. I wish I could find that essay now; I’d link to it here. The gist of it, though, was designing puzzles as stories, coming up with a description of the intended player experience before sitting down with the level editor. Things along the lines of, “The player walks into the room and sees roach queens ¹The most basic monsters in DROD are the giant cockroaches, which just charge at you in a straight line. Roach queens are roach generators. They flee before Beethro and create new cockroaches after every 30 moves. in every corner, positioned behind force arrows where they’re inaccessible. At first, this seems impossible: the player can’t reach the queens to slay them. Then the player notices…”

Good advice or bad? All I can say is that it seems to have worked pretty well here.

Having played the oldest games on the Stack, it’s meet that we now continue with the newest: the first game on the Stack to be released after I started this blog. DROD: The City Beneath is a game I’ve been looking forward to.

I suppose I’ll have to explain the DROD phenomenon a little, because it’s way too indy to attract any significant media attention. Known to connoisseurs but not sold in stores. The word “cult” probably belongs in here somewhere. Originally known as Deadly Rooms of Death, it’s a turn-based puzzle game in the dungeon-crawl idiom, its gameplay somewhere between Gauntlet and Sokoban. The goal is simple: kill all the monsters. A single blow from your Really Big Sword will destroy any living thing in the square it touches. The controls are also simple: use the arrow keys to move one square in any direction, and the “Q” and “W” keys to rotate 45 degrees, swinging your Really Big Sword ¹Yes, it has to be capitalized like that. Be grateful I have enough self-control to refrain from adding a trademark symbol. as you do so. It uses these two simple things to create complex puzzles. The basic way the game works, from the first episode onward, is that most levels introduce a new monster type or terrain feature and then exploit its puzzle potential in every imaginable way. When its potential is exhausted, you proceed to the next level and get a new puzzle theme to explore exhaustively.

The first game had a simple storyline involving Beethro Budkin, dungeon exterminator, being hired to clear out the levels below the castle of one King Dugan. It left one hook for future adventures: one room had a door that could only be opened from the other side. The sequel, Journey to Rooted Hold, had Beethro getting through that door and discovering to his shock and surprise that the game had a plot. It seems that the accretion of additional levels to the bottom of Dugan’s dungeon in successive versions of the original game isn’t just a natural phenomenon, but the activity of an underground empire founded in the pursuit of knowledge — a hive of secrets, seemingly pointless activity, and endless bureaucracy. NPCs were introduced, Beethro’s nephew Halph (who assisted Beethro with some of the puzzles) started acting creepy and disappeared, a voice from a vast pit muttered cryptic nonsense. The City Beneath, the new episode, picks up where that left off, with Beethro arriving at the empire’s capital. The city is a hub of pure scenery and NPC interaction where Beethro isn’t even allowed to use his sword, with puzzle areas around its periphery. In a way, this hub section reminds me of Knytt, an experimental work that’s more art object than game.

That’s the basics. More details will follow, when I’m not in a hurry to get back to playing it. This is a real 5 AM game.

In a reply to an earlier post, corto writes:

I too am a fan of games modeling other types of games inside themselves. The Sokoban levels in nethack are another example – I’m trying to think of others.

I have to mention Heaven and Earth, a game from 1991 featuring abstract puzzles by Scott Kim. There are 12 types of puzzle in the game, several of which are used to model other types of puzzles.

For example, one of the types of puzzle involves assembling a given pattern out of pieces made of line segments on a grid. This is straightforward at first: you look at your pieces, you look at where they might fit in the target shape, you put them together. It’s like tangrams, except that the pieces are made of lines and are allowed to overlap. But after a while, you get a puzzle that’s not like that at all: instead of the target pattern being a composite of the pieces, it’s just the same disconnected pieces, arranged differently. Suddenly the constraints of the space matter. The thing that makes it hard isn’t figuring out which piece goes where, but getting them were they belong. If you allow two pieces to touch, they stick together, which isn’t what you want. And the meager empty space isn’t large enough to contain an entire piece, so you have to shift and shuffle them around. In short, it uses the rules of a pattern-assembly puzzle to create a sliding-block puzzle. Again, this is not the only example in the game.

I notice that Mac and MS-DOS versions of Heaven and Earth have been made available for free download by its creators. The DOS version runs under Windows XP, but had no sound when I tried it. Presumably VDMSound would help there.