Throughout the first episode of Quake, there are moats and bridges. Each has varied mechanical functions, depending on the level. Thematically, what separates a bridge and moat from similar structures like catwalks across hazards is that they functions as a threshold the player must cross. At their best, these thresholds signify a first step in an attack against an enemy stronghold. This frames the player’s actions within the fantasy of storming a castle, which gives the player unspoken goals: get to the heart of the fortress and take it.

Compared to other level starts in Quake and in Doom, the bridge and moat setup offers better context for exploration and combat. Keep in mind that as we go through some of the examples from this episode, not all have equal impact, and players may experience these areas differently than I describe.  This is because the effect of this motif depends on level design working with game design and drawing from a player’s cultural awareness. This is not a fundamental property of bridges everywhere. With a different set of verbs, such as the cleaning verbs of Viscera Cleanup Detail, players could have different reactions to identical level design.

This is also just one motif we can look at with Quake. We could find even more riches by considering the design of the keys and locked doors, or by looking at how the game introduces each new enemy, or by studying each trap the levels springs. For a 21 year old game, there is still so much to learn from its design!

E1M1: Slipgate Complex by John Romero
We experience the first moat and bridge after descending an elevator from an enclosed tech base art set. Due to the orientation of the button in the elevator, the player will be looking to the left of the bridge and will hear the enemies before seeing them.

First glance of the moat and bridge in E1M1

Turning right to face the alerted enemies, the player sees the moat and bridge in the middle of a box canyon with organic green and brown tones in their textures. Across the moat the player sees another tech base and also sees the alerted enemies.

From gameplay, the moat functions as a funnel for navigation. We are able to see our enemies and predict their path to us. The moat in this box canyon environment lets the player cull extraneous information and focus ahead on the enemies.

The moat and bridge up close

One of the enemies is a Rottweiler, which we hear bark into its alert state. Because the Rottweiler melees, it crosses the bridge immediately to enter attack range. The bridge has railings along the side which partially obscures the Rottweiler and prevents a direct attack. The other enemy is a grunt with a slow shotgun attack, which can hit the player across the moat. The player only has a shotgun at this point, which has a slow refire rate and is less effective at range. If the player chooses to shoot at the Grunt as the Rottweiler crosses, the player may not have time to respond to the Rottweiler before taking damage, and the Grunt will still be alive. As the second space of the first level, this moat and bridge introduce the player to target priority, which is a recurring theme of Quake’s combat design. The level reinforces this idea in the next room where the player faces several Grunts, a Rottweiler, and an explosive barrel.

This moat and bridge also introduce the player to their first secret area. If the player is still becoming familiar with the controls of a 3D First Person Shooter, there’s a good chance of falling into the moat, and the only way out is through a secret area with a reward. Players who are familiar with 3D first person controls should also notice the secret easily. Either way, discovering this secret tells the player about the way the levels are structured, and that there are rewards for exploration.

Walking in the moat in E1M1

Deeper into the second compound we see a second moat and several Grunts across from it. The water in this moat is a putrid green and will damage the player. There isn’t a bridge until the player presses a button, at which point it slides out and any living enemies will start crossing. This setup does not serve the same thematic function as the first moat and bridge, but mechanically it is part of a conversation the level is having with the player. Both moats serve a similar role to the pits players must jump at the end of Super Mario Bros 1-1. The first obstacle teaches the player in a safe environment. The second obstacle teaches the player with a risk. From then on, the levels use this established pattern as a building block for more complicated setups.

E1M2: Castle of the Damned by Tim Willits
As soon as the player starts the level, they see they are in a room with a Grunt and an Ogre facing toward a large doorway. On the far side of the room is a moat of dirty water and a wooden bridge that the Ogre is crossing. As a way of introducing this new enemy, the level lets the player decide what to prioritize and when to start the fight. If the player waits, the Ogre will continue its patrol out the door, up some stairs, and around a corner out of sight.

The player also starts on a higher platform from the two enemies. If the player immediately enters combat, they will have the advantage. Specifically, the Ogre enemy fires a projectile grenade that bounces several times before exploding, or will explode on direct contact with the player. Because the Ogre is on the low ground, he may miss, hit the edge of a stair step, and cause the grenade to bounce back toward himself. This setup is the safest way to fight an Ogre.

Visually, the environment reads as an old castle or dungeon. If the player stops to study the architecture, it doesn’t make sense as a real castle. Since the player is in a room that is presumably inside the castle, it makes no sense to have a moat and bridge here. There is no apparent water source or drain. In short, this moat and bridge fails the “who built this?” “Why would they build it this way?” and “What happened here since it was built?” questions we expect most modern AAA games to answer.

However, for the experience of Quake, answering these questions does not matter. The level wears the skin of an old castle, much as sections of a themepark wear their facades, or as dreams recreate just enough familiarity for us to see them as real. If we transplanted the game mechanics of Thief, then a kind of architectural semi-realism would matter more because the player would need to recognize rooms by their function (bedroom, kitchen, parlor) and recognize the value of loot associated with those locations. Realism for these games only matters to the degree it serves the whole experience, and for Quake that means spooky, dream-like castles and dungeons, not real ones.

Returning to the moat and bridge, since this is only the second level there is still a good chance the player may fall in by accident as they learn the controls. The bridge itself has ramps into the water that allow the player to easily walk back up. Although the water is dirty instead of a clean blue, the player does not take damage. Unlike the first moat of E1M1, the water here is deep enough that the player must swim. There is only real danger if the player falls into the moat before killing the Ogre. The Ogre’s grenades sink, and the Ogre will block the exit from the water where the player must enter range of its chainsaw melee.

For players who discovered the secret in E1M1, E1M2 offers a subtle callback. As with the first moat and bridge, there is a secret to the right. With E1M2, players must shoot the wall to discover it, and there are no hints other than knowledge from the previous level.

Moving deeper into E1M2, there is a large room with several balconies, a large pool of dirty water beneath it, and a catwalk crossing to the far side. This space functions more as a combat encounter, or a room that players inhabit for a duration, rather than the threshold function of the moat and bridge. There are many other spaces in Quake with extended catwalks and hazards to either side, but they operate as a separate motif from the moat and bridge.

One of the catwalk and hazard setups in E1M2

E1M3: The Necropolis by Tim Willits
In the third level, after the first few areas of combat and an introduction to a new weapon and some new enemies, the level presents us with a really neat setup. This is one that blurs the boundary between my definitions of bridge and moat versus catwalks and hazards. Here we have a bridge extending to a tower, which has another bridge extending to a platform with a gold door. Below these bridges, instead of a moat we have a large room with water, and the player can see the gold key on a patch of dry land.

This setup informs the player about their goal (the locked door), and about one of the steps to achieve that goal (the gold key). From here, the player’s navigation through the level has context. Even if the player loses track of where to go, as they might if they jump into the pit for the gold key, the larger goal gives some direction. If, for example, the player jumped into the pit and found a staircase leading down and another staircase leading up, the player understands they must return up to complete the level, and can assume that the staircase down is toward a secret instead.

E1M4: The Grisly Grotto by Tim Willits
At the end of E1M4 we get a fun reversal of the moat and bridge motif. With the other occurrences up to this point, killing the bridge guards and crossing it are the first steps into enemy territory. With E1M4, the bridge is the last step of a map. The player leaves a castle-like structure to cross a bridge to an organic gap in the cliff side. This setup is as if the start and end of the level were reversed, or as if the player is finally exiting the back of the castle that they entered in E1M2.

E1M5: Gloom Keep by Tim Willits
This is the most obvious moat and bridge setup of this episode. Immediately on entering the level, the player sees a huge fortress, a front door framed by two massive pillars, and the bridge itself.

Where this use of the moat and bridge falters is that that the player starts on the bridge. The player does not get to decide if it is time to cross and do battle, as the player did in E1M1 and E1M2. This weakens the alignment between the player’s actions and the theme of storming the castle. This setup also reduces the possibility to anticipate the fight ahead

Aside from this, the setup is familiar. If players fall of the bridge, the water is safe and will lead around to a side entrance in the castle. If the player swims underwater to the right of the bridge, they will find a secret cave with a health item as a reward.

E1M5 also is the last level in the episode with a moat and bridge…

E1M6: The Door to Cthon by American McGee
But I can’t talk about Quake episode 1 without talking about E1M6! This is my favorite level in the game. Like McGee’s E4M1 in Ultimate Doom, this is a combat puzzle box where the player teases at various pieces to see what unlocks and what new traps will spring.

Definitely not a moat and bridge?

E1M6 doesn’t have the moat and bridge motif, though, unless we count this diving board platform to reach the gold key? No? I guess I’ll have to save discussion of that one for another time.

Thanks for joining me on this look at one facet of the design in Quake’s first episode.

Cheers,
Andrew

Correction: previous version incorrectly credited E1M5 to John Romero, instead of Tim Willits. Fixed 11/24/2017 9:55pm

 

Earlier this month, Strafe came out. It styles itself as a first-person-shooter in the tradition of Doom and Quake. The tagline even places it in the year of Quake‘s release: “Bleeding Edge Graphics and Gameplay (C)1996”. Strafe falls short of that goal. There are bugs and framerate problems, but there are also design problems that I think are worth dissecting.

In case you aren’t familiar with Strafe, here’s the launch trailer:

Skill Checks and Loops

When I want to understand what a mechanics-driven game is about, I look at the skills it checks and how it checks them. Generally, “skill check” is a term from tabletop RPGs where a gamemaster asks a player to roll some dice based on their avatar’s skill and determine where the action falls between success and failure. For digital games, if we think of the designers as the gamemaster, then by asking what kind of skills the gamemaster checks, we can determine what kind of game they want to run.

We can also think about the player’s actions and skills as part of several layers, or loops, based on how frequently each occur. The first loop is second-to-second decision-making that players internalize as they learn the game’s mechanics. The second loop is minute-to-minute decision-making, which can also become habit through practice. Additional loops can exist for session-to-session or hour-to-hour.

(Mind that this framework doesn’t work for all games, especially those with narrative focus.)

Skills in Strafe

The first loop is about surviving second-to-second gamepaly. The skills in this loop build on each other, and as players internalizes these skills they can shift conscious attention to higher-order skills.¹

1. Controls and input: moving and shooting in 3D environments
2. Kiting: moving through safe parts of the map with enemies chasing out of reach, like pulling a kite by the string. (Because most enemies in Strafe are melee, players can kite large groups and clear them without taking damage.)
3. Seeing the signal in the noise: identifying acid pools, fires, enemy projectiles, and enemies against the environments and debris.
4. Map knowledge: avoiding dead ends or unsafe territory while kiting enemies.
5. Target prioritization: identifying the enemies that pose the greatest threat, and changing position or weapons to kill them or change the priority.

As the player gains mastery of the first loop, they begin learning the second loop of skills required to survive the minute-to-minute gameplay.

1. Resource management and exchange: players can spend scrap to buy ammo and armor, but players can also “spend” health to preserve ammo and gain positioning, or spend ammo to preserve health or shields. Players can also spend scrap for credits, which players use for items, which in theory help the player preserve health or ammo.
2. Signal and Noise during map exploration: identifying resources among the gore and trash is an essential optimization.

The third loop for Strafe is session-to-session, trying to beat the game. With this goal in mind, there are ways to activate teleporters at the start of each zone and skip to them at the start of the next run. This serves as a partial success state, or a checkpoint toward the larger goal. Spelunky has the same logic for its zones. Even if a player knows they will fail their run, possibly due to bad luck or a few errors, this gives them a reason to continue.

At least that appears to be the design intent. In practice, it is unclear what steps are necessary to fully repair any of the teleporters. Skipping ahead also limits the number of powerups and items a player could earn in a run, which makes the boss more difficult.

Based on the global Steam Achievements, this third loop is not successful. More people have completed the game without teleporters than have fixed the teleport in zone 2. (The achievements for fixing the teleporters in zone 3 and 4 are at 1.5% and 0.5% respectively.)

Bad Skill Checks

One way that skill checks fail is when there is a consistent, repeatable solution. This becomes boring quickly if there aren’t other challenges for the player. And when the skills in the first loop become boring, the second and third loop are often insufficient to keep the player playing.

If the goal is to create a game that players spend a long time playing, one solution is to add depth by improving the existing skill set. (To mix metaphors, raising the skill ceiling adds depth.) The other solution is to expand the low-level skills by adding more variety and ensuring more permutations.

In Strafe, combat has the same solution for most enemies and levels: eliminate ranged and acid enemies first, then safely clear melee enemies while kiting them. The level segments create two variations on this strategy. Tight layout features like the bridges, trenches, and hallways of zone 1 let players funnel enemies and turn the game into Duck Hunt (all shooting, no moving). The arena layouts in zones 2, 3, and 4 let players split groups to divide and conquer. Once players learn these simple strategies, there are few challenges left in the first loop of gameplay and players have to shift focus to the outer loops.

Another way that skill checks can be faulty is when they have a binary fail state. If a player died in one hit, then the player health would be a binary state: alive or dead. Another example of this is in stealth games where being discovered means instant mission failure. Because Strafe has a range of health and armor, and because none of the enemies can kill in one hit, there is room for partial failure in combat. This failure allows for recovery, which creates tensions. Partial failure also lets the player measure their progress toward mastery.²

This brings us back to “seeing the signal in the noise” as a skill check. In classic arcade games, isolating the information from distractions can be as important of a skill as reflexes.³ A player’s ability to overcome this kind of skill check is measurable in recovery time. The problematic signal and noise skill check in Strafe is different. When identifying an enemy or projectile against the environment, the player either sees it or doesn’t; there is no partial failure here. Worse than enemies and projectiles is trying to identify resources among gibs, gore, and trash.

For example, in the above screenshot from the arena mode “Murderzone”, there is some valuable scrap among the corpses, randomly dropped from one of the kills. This is not obvious without careful inspection, or by accidentally walking through it. In the main mode, scrap separates a successful run from one where a player died for want of ammo. Due to the noise, finding scrap can feel arbitrary instead of skillful, which limits the resource management skill of the second loop.

In zone 1, there are also keycards needed to progress through levels, or sometimes there are dismembered heads that need to be matched to an eye scanner. When trying to find a keycard amid the gore, there is no partial failure or partial success. The result of these item hunts is a slower pace with no gains for it.

Another way the game throws the signal and noise skill check at the player is with enemies that leave permanent acid pools on the floor and walls. These acid pools make no sound and deal a small amount of damage per second. As a result, a player who is backpedaling or strafing can take directionless damage and not know whether it is a hazard or a melee enemy, which are also sometimes silent. This clutters the mental map a player has to maintain while fighting, which burdens memory instead of attention.

By comparison, enemy projectiles in Doom have a sound effect attached to them with a fake Doppler pitch shift. The projectiles also play a sound when they hit a wall. These pieces of feedback allow a skilled player to dodge projectiles that they aren’t watching, and know when that information is no longer relevant. The skill in Doom is about threat priority and player attention, not about memory.

Another factor is missing feedback for a first person camera. With a different implementation, the acid’s effect on the player’s resources of health, shields, and map positioning could be an interesting obstacle. For example, Diablo 3 has similar acid-pool enemy attacks that prevent the player from kiting, or force the player to take the damage in exchange for positioning, but Diablo 3 relies on a top-down camera where the effects are always visible. Because Strafe has a first person camera, the same kind of acid-pool attacks require different skills from the player.

Closing Notes

There are other problems with Strafe—ambiguous feedback around upgrades, bad balance around weapons and items—but these are not fundamental. Some weapons and items make combat easier than others, but the combat remains the same. Tuning the balance here would affect difficulty, not player behavior.

The purpose of this framework is to identify what a game is about based on where it checks the player’s skill. Strafe has kiting, target prioritization, and map positioning; these are the basics of Quake, and there are some good moments here. But once players master these basics, the game is about signal and noise and arbitrary resource management. The strafing in Strafe is the easy part.

A puzzle to gnaw on:

The problems with Strafe‘s acid and gore could be fixed at an aesthetic cost (remove or reduce the gore, make the scrap more obvious, add sound to the acid pools, let the acid fade after time, etc.). These changes would affect the play experience and identity of Strafe, remove its rough edges. But if all the rough edges are gone, what does it mean to make a 1996-styled FPS in 2017?

Footnotes

¹ My thinking on this topic is shaped by a GDC talk Matthias Worch gave in 2014, “Meaningful Choices in Game & Level Design”, http://www.gdcvault.com/play/1020570/Level-Design-in-a-Day

² In stealth games there is a related concept of expanding the failure-spectrum to create more drama. Randy Smith wrote about this for Thief 3, which Robert Yang summarized here http://www.blog.radiator.debacle.us/2011/07/dark-past-part-4-useful-post-or-randy.html Despite the obvious benefits of this idea in stealth games, this is a concept I seldom hear discussed for action games.

³ In Super Hexagon—which borrows from the arcade tradition of Tempest and Asteroids—the hue-shifting, value-inverting, and screen-spinning in themselves cannot defeat the player, but they can confuse and misdirect. Mastering Super Hexagon becomes a matter of learning to see what is real, and learning to see past what is not, a concept we also see in puzzle games like The Witness.