Designing Highly Replayable Stealth Levels for Payday 2

The Making of Murky Station: Payday 2

Payday 2 is a four player cooperative first-person shooter with RPG elements that centers around robbing banks and stealing rare loot. It was released on August 13, 2013 and has since shipped over 50 DLC packs and counting. With a thriving subreddit, it has consistently been in the top ten games played on steam. Today, I wanted to talk about my adventures designing stealth levels for Payday 2 before leaving Starbreeze in January 2018. While parts of this article are specific problems and solutions for Payday level design, I made sure to discuss them in a broader sense. The skill level of this article is for junior to mid-tier level designers, if you are a senior designer some of this article may sound familiar to you.

I'll start off by saying that Payday's stealth mechanics are not perfect and can be flawed in some areas, but I wanted to focus on the decisions behind the map design, specifically for the heist Murky Station. I'll also break down how we consider using RNG (randomization), and the ways we apply it to objectives and mechanics to keep the level fresh and replayable. This map took 6 weeks to make between 2 people. My partner took the role of Level Builder / Environment Artist and I took the role of Designer / Scripter. Between the two of us, we figured out the scale of the project based on the needs of our studio. The idea was to create a small heist that took around 10-15 minutes to finish with high replayability. There's a lot to go over, so let’s get started!
 

Let's Start From the Beginning

Before we start drawing or building layouts, we make the call if we are going to create a Loud level (combat only), Stealth level (avoid combat), or Mixed style map. For the short period of time given to us, we decided to stick to stealth only. Making this decision early on helped us create better movement options for the player and focus our efforts towards balancing patrols and objective placement. We decided that the theme of the level was a small train depot run by a group of mercenaries shipping large weapons. The main objective was to infiltrate the depot and steal an EMP bomb. Keeping the objective simple and intuitive is important in multiplayer games where players can drop in and out of the experience at any point in time.

We decided to shoot for 10 - 15 minutes of gameplay. Breaking down our main objective into smaller sub-goals that could take about 2 minutes each (this is based on our extensive knowledge of payday 2). It should be noted that this time assessment will change once the player has completed the level a few times. These numbers tend to get cut by a third, or in some cases, by half. With our main objective in mind, we can construct a simple flow diagram for the heist and start to think about possible dynamic and RNG elements that can be used to create a re-playable experience.

(This is a scripting example from our editor, each entity has it's own function)

Testing your ideas before scripting them? Wait... What?

Since 90% of Payday levels are hand scripted, it's important we don't waste time building the wrong things. Testing your objectives and complicated RNG elements has to be fast and efficient. The last thing you want to do is build an entire system and find out it sucks. Most of the time you don't even need animations or even a model to properly test your ideas. At such an early stage some floating debug text will do just fine. You might be asking, what if I don't have debug text or the ability to script? When playtesting levels for Payday 2, a lot of the time we'll get a simple block-out done and then ... here it comes ... pretend we're doing the objectives.

It might sound crazy (and not everyone can get through it without laughing) but we'll have one of the designers act out the role of Bain, our mission giver, and just spout objectives at us. We'll move through the space and pretend to see guards or hack laptops and delay time based on things we expect to happen. You can basically break down how your systems might work and try out a few possibilities. For example, knowing that you might have two escapes at either side of the map gives you enough knowledge to make pretend decisions. Telling your fellow devs the van is arriving up top and pointing out where to secure loot can help you find out if a location is interesting for the escape or not.

Even though the artists might giggle, or people from the other teams walking by stop and wonder why they can't see that hoard of enemies. It really works, and can often steer the level in the right direction and prevent us from investing too much time on the wrong objectives. Now, I know this approach won't work for all studios or situations, but all I gotta say is... don't knock it till you try it...  

Constructing our Sandbox Layout

Now that we've pretended to run through our objectives and have gotten used to our basic block-out, let's talk about the layout we built for Murky Station. We went for what i'd like to call "the onion approach", which is pretty much what it sounds like. You'll have multi-layered rings that give you the sense of progression towards the center (or a goal). Essentially, we use the outer layer as the player start and each sub-objective is based inside a different layer until the player reaches the main objective (at the figurative center). This approach is very useful when working with sandbox type levels, especially when the player can virtually go anywhere they want.

Side Note: We also layer our music track each time a sub objective is finished, creating more suspense and a sense of agency.

You can see that the outer onion layer is the player spawn (colored green) on the overpass which gives them a full view of the trainyard. From here they can study patrol routes, train-car positions, and possibly objective locations. The overpass can also be used by a player with a sniper rifle to mark guards in the different lanes, helping provide accurate information on guard positions for the players on the ground floor.

The next layer is breaking into the train yard through a fence around the perimeter. The fence is here to guide the player and give them a visual boundary for the "safe zone" (where no guards patrol). The next layer is searching the train cars to discover where the main goal is hiding, followed by breaking through the vault doors inside of the trains themselves. These onion layers have to be carefully managed to give the proper impression to the player. Too many layers and you might confuse the player or make them forget what they're doing, too few and you might leave them feeling unchallenged or unaccomplished.

Player Mobility is Key!

Mobility is key to providing players opportunities to express themselves and make better decisions while traversing a level. I felt that it was pretty important for Murky Station to allow for different play styles ranging from slow and methodical to fast and dirty. The last thing I wanted was to force players to play a certain way or for the routes to become predictable and linear. In order to do this, I spent the first week of development prototyping and testing out different layout ideas that would maximize paths and choices for the player.

(Here is a simplified top-down of the routes in the train yard area)

It became obvious that we would need to allow players to traverse through and under the trains as they cover most of the real estate in the train-yard. Unfortunately the older train assets were not built to go underneath, but lucky for us, the nighttime setting of the level would cover up this fact. There being only 2 of us on this project, I took a crash course in Maya and cleaned up the bottom half of the trains by removing collisions and remodeling them for readability purposes.

The next challenge was to teach the player they could hide under trains and be safe. Payday players haven't been under the trains in any other heist up until this point, so we needed to call attention to that but also show them it was a safe place. Making these spaces dark and in the shadows helped create an illusion of safety but also made it harder for players to find them.

To help solve this issue we added yellow caution tape as a trim and a dim red light under the wheels to catch the players eye. These combined elements would then be used as visual vocabulary in other parts of the level to teach players something should be explored.

One of the other ways we added more routes to the level was to build a ventilation system in the lower tunnels. Leveraging the fact that this was a stealth level to create these smaller spaces, especially since they didn't have to accommodate 40+ police officers. The vents allowed players to safely view guard patrols, search for objectives, and move loot. To prototype this, I built a modular vent system using basic mock-up units that allowed for rapid construction and testing. Funnily enough, the first iteration of the vents was too small and caused players’ bodies to clip through the floor. I was able to rework my mock-up units and we settled on standing height instead of a crouching one. Once again we used yellow caution tape as our visual vocabulary to highlight the vent entrance on the wall.

Modifying the trains and vents is one of the factors that contributed to the map’s success and gave new players more confidence to explore the trainyard and lower claustrophobic tunnels. So now that we've explored the different possibilities for movement and giving the player more choices, it's time to buckle down and get our randomization system built.
 

Randomizing Objectives to Maximize Replayability

RNG is one of the core pillars of Payday, so every decision we make is looked at through a lense of RNG. We strongly believe randomization should be meaningful to gameplay and not just added for the sake of it. It’s important to ask questions like: was it worth changing all the cups in your level? Did you gain anything from swapping out all of your cars and buildings? Was creating a third entrance valuable to the level? Maybe one day we'll completely randomize every object in a building down to the smallest cups, but in a game like Payday I personally feel these types of things have diminishing returns and can often ruin a planned design.

When working with RNG it's important that you ask yourself as many questions as possible to start with a strong foundation, especially if you plan on finishing on time. Something I often see junior to mid-tier level designers forget is to build for scope and set priorities on their objectives. It might sound trivial, but forgetting your priorities can send you down a black-hole that eats away all of your time.

So how did we go about adding RNG into Murky Station? Breaking down our objectives, we can start to consider what RNG options are available and doable within our one month time frame. I've also labeled them with my personal priorities (low - high).