Deus Ex: Mankind Divided allows players to approach the game in any way they want, be it by creating chaos, by being stealthy, or anything in between. Senior Level Designer Julien Hantz explains how Eidos-Montréal created quests and levels that supported this kind of gameplay.

Designing the quests for a Deus Ex game is a great and unique exercise. This is because it is done by giving players the opportunity to play the way they want. This seems like a bullet point that we see on the back of the box of a lot of games, but only a few really deliver on that promise, even open worlds, who generally offer a systemic experience between very linear missions. In Deus Ex: Mankind Divided, we put player’s choice at the core of every step of our design process.What does »player’s choice« really mean in a Deus Ex game? It means that, for any given mission, players will be able to reach their objectives by using multiple paths, completing them by different means while having the freedom to choose how they will proceed past each obstacle: »Do I play stealth, avoiding any conflict and never being spotted? Do I go in guns blazing? Do I neutralize my enemies by being lethal or non-lethal? Do I use augmentations, or not at all? Do I stick to one strategy all along, or do I adapt to the situation and do a mix of everything during one single mission?«

As quest and mission designers, our role and commitment is to make sure that, every time until the end of the game, all these options remain available and possible. When we say that it is possible to remain stealthy during the whole game, even more so by never being spotted and/or by not neutralizing anyone, it needs to be part of our production checklist. If we say that you can also complete the game without ever upgrading your character, it is also something we need to take into consi­deration when building the game world, which includes the different paths leading to each objective. Failing to do so is not an option, and we wouldn’t have shipped the game if even the smallest section of the game didn’t meet this core requirement. Having all the choices in the world isn’t worth a lot if the game doesn’t react to the player’s actions. For all quests and missions, we needed to think about how to give player’s constant feedback regarding their playstyle. This can be done through some subtle changes in future conversations or briefers, adding completely new objectives or environment setups, or even a direct tie in with the main story. It seems to be a given in games in 2016, but think about it for a moment: how many games provide you with this amount of freedom? Not a lot. Why? Because it is challenging to create a simulation that responds to the player’s actions, and it is very costly in terms of production. This is because a lot of variations, along with a lot of specific content, needs to be created, but a good amount of it will never be seen or experienced by players who only play the game once. While this seems like a lot of constraints, it is also what makes creating a Deus Ex game such a fulfilling experience.

Outside of the main quest, players can pursue any side quests they like. If completed, some of these missions might make their lives easier along the way. However, if they choose to ignore them, the game won’t punish the player.

Macro Design:
Missions and Objectives based on Player’s Choices

In the world of Deus Ex, missions and objectives are never set in stone. They can be updated, cancelled, or failed without leading to a »game-over« or forcing the player to reload his game. We always need to make sure the player will be able to explore, roleplay, fail missions, or even break the rules of the game while the story continues to unravel its secrets. We need to give the player the feeling that the game world reacts to his actions, but also lives and breathes without them. In order to keep things fresh, we didn’t have one set way to design missions, and every mission or quest had its own structure, depending on its place in the story. Of course, we have objectives that, whatever the player does, will need to be completed in order to tell our story. However, let’s focus especially on how player’s choice can affect the way we create our mission objectives.

Optional Missions or Objectives
Optional missions or side quests are important because they are independent stories, designed to reinforce the themes of the game while adding depth to the game world. However, they are also important because the player is free to ignore them. There are situations within the game that exist despite the main mission and actions of the player. Completing them will make the world richer, will give the player more means to express themselves, but not completing them, or ignoring them, shouldn’t lessen the core experience for the player. Even if they are ignored though, the presence of these characters and optional areas of the world gives a greater sense of depth to the game, encouraging replayability.
Optional objectives within main missions are different, mainly because they will eventually challenge the player on his playstyle, provide opportunities to get additional XP, or help them to have a better understanding of the mission. We talked earlier about player’s choice, and the possibility for one player to stick to one strategy throughout the entire game. Having the freedom to play the same way from start to finish is good, but being morally challenged while doing so is even better.
To give you one example, at the end of the game, there is one mission where terrorists have infiltrated a security detail during a public event, and you need to uncover what their true plans are. One optional objective is to neutralize all of the fake security guards, providing protection to a large crowd of innocent civilians before the terrorists can act upon any of their plans. It is totally possible to ignore this objective, but doing so will lead to the deaths of many people. In that case, this optional objective will challenge stealth players, who usually tend to avoid confrontation. Doing nothing has consequences, and therefore creates a dilemma for players who already have a well-established playstyle.

Preemptive Objectives
Another great example of objectives based on player choice are preemptive objectives. They are particularly interesting because, again, not a lot of games give you the opportunity to complete an objective that hasn’t been given yet. Most games are based on a linear structure, where locations and setups are made available the moment the game tells you to go there and complete a specific action.

In any given situation during the game, the player can choose to start fighting, or to stealth past enemies – this was a big challenge, as both the characters, and the game world as a whole, had to react accordingly.

One example in Deus Ex: Mankind Divided is that, at the very beginning of the game, if you decide to ignore your first primary objectives and explore the city, you may end up at Otar’s casino, where it is possible to steal the calibrator (an item critical for one of the games side quests) right away. Then, when you talk to Koller (the one who assigns you this quest), Adam answers that he already got it. It seems trivial, but in most games, the calibrator wouldn’t even be present in the location yet, or accessing the casino would have been impossible. This is a little thing, but it is very typical of a Deus Ex game.

Conditional Objectives, Objective Updates, and Hidden Objectives
From the get go, the missions, and their objectives, are designed in order to make sure that no matter what happens, the only thing that will end the mission is the player’s death. To do so, we create diagrams where everything is planned, and every objective update is written in advance. Of course, we have a few tricks to make sure the player will end up in some bottlenecks, allowing us to be able to tell a story in the end. However, everything that happens in between has to be possible.

That’s why we always think about the worst thing that could happen, and create our objectives accordingly. Most of the time, a player will only see a relatively simple succession of events, leading to just a few objective updates. But under the hood, we planned every action he could have done, and how far he could have gone within the limits of our simulation. One of the most beloved side missions of the game, »The Harvester«, has an amazing number of ramifications. In it, depending on what the player discovers, what augmentations he has, and what choices he makes, the objectives given and their descriptions will change to highlight what he has done. The mission itself can be really short, even ignored, but can also last until the final act, and can even end up in a boss fight (or not!). What makes this game stand out is that every player will be able to talk about their experience, and each experience will undoubtedly be different.

As the player is free to choose which augmentations they want to use, the designers had to be careful when balancing those powers, ensuring that none of them became absolutely vital or overpowered.

In the end, what matters for us designers is to really make sure that every mission feels unique for the player, that the objectives are tied to the player’s choices, and that all the game gives the player enough feedback on how he is playing. While creating missions that can be ignored, failed, or made really short depending on how you play is not really a problem for side missions, it is a completely different story when creating objectives that are tied to the main quest. To give you another good idea on how we think about player choice and how it affects the way we create main objectives, there are a few examples of how we tried to push the limits and support players who don’t like to play by the rules.
In the final mission, one of the first objectives is to go talk to a receptionist. It would have been easy to force the player to talk to this guy through a scripted event or a small cinematic, but instead we kept the receptionist in the game world, with the risk that the player would ignore them, or even kill them. When you choose to let the player do what he wants, it multiplies the number of possibilities. Therefore, you need to make sure that everything is thought of, and that every line of dialog is planned and makes sense. For example, there needs to be an objective update for each possibility: if you create chaos before talking to the receptionist, if you create chaos after talking to the receptionist, if you bypass him, or if you talked to him. However, this is only the beginning, since the entire map and its succession of objectives is based on giving the player the right to ignore or disobey most of them.

Another example concerns the final boss fight. In most games, when you get to the boss room, you are stuck in the room until the combat is done. In our case, it is absolutely possible to escape the room, complete your other objective, then go back and finish what you started. Again, it is really demanding on the design team, because all objectives must be thought out in every possible way, and dialogs must still make sense.
One of the most challenging, but also rewarding, parts of creating quests and missions for a Deus Ex game is to let players do what they wouldn’t be allowed to do in most other action-adventure games. Mankind Divided is not an open world, and players still need to follow a

somewhat linear story, but the way they complete objectives, and the way the objectives always adapt to the players’ choices, makes it a very unique game.

Choice and Consequences
Having the objectives adapt to the players choices is one thing, but it’s another to have the environment, and the people who are populating the world, react to every major

Players have complete control over how they choose to play the game, with them also having the freedom to select the powers or equipment that match their play style. Therefore, the AI in the game has to be able to react to anything the player does.

action undertaken by the player. To give a few examples, the content of newspapers/emails will change depending on how some objectives are completed, conversations between NPCs or with major characters will change depending on the players’ actions, and some gameplay situations will also be different. If the game reacts so well in terms of objectives and conversations, it is because a lot of work is done by the Level Designers and Narrative Designers to think through, and plan for, every possibility. It is hard work in terms of planning, iterations, and testing to make sure that every piece of the puzzle is well put together. Another part of the work of designing a quest or mission is to create an environment where players will get to express themselves throughout minute to minute gameplay, choosing, in a very systemic manner, how to behave and go through a mission by using stealth and/or combat.

Minute to Minute Gameplay:
Be a Ghost, a brutal Soldier, or anything else in between

One of the main features of Deus Ex is to give players the freedom to choose between stealth and combat, and to provide them with the ability to change their strategy on the fly. All of this is possible because of the way the layouts are designed, and the way the AI works.

Layout Creation and Cover Placement
The cover system supports both playstyles, allowing stealth players to stay hidden and easily break line of sight, while providing combat players with strategic cover, giving them an opportunity to avoid incoming fire and flank their enemies. The layouts are all designed with player choice in mind. Even if the layouts contain more than one path to get to one objective, there is not one path for action, one for stealth, one for hacking, etc. While some paths will be made to accommodate one playstyle over the other, whatever the path you choose, you should always be able to play the way you want. The main reasoning behind that statement is that, when players do choose a path, they won’t be able to immediately recog­nize if they are taking the path which will suit their playstyle or not. In a game where improvisation is king, we need to make sure that every player has the means to express themselves, without relying on the principle of trial and error.

If the player creates chaos somewhere in the game world, they will quickly realize that NPCs, or even newspapers/emails, will reflect their actions. Eidos-Montréal was keen to create a living, breathing game world.

Every single encounter must take place in a layout that allows players to:

  • Observe the main threat from a safe zone without ever being spotted (if staying in cover), allowing them to plan their infiltration or attack. Move from cover to cover in a very easy and natural way, either bypassing their enemies, or taking them down in the most efficient way possible.
  • Be able to retreat (if seen or overwhelmed), change their tactics, and get back into the action.
  • These simple principles and gameplay loops are valid for both stealth and combat players. Having open environments where it is easy to read the action, easy to look for vantage points, and easy to find places to hide while in difficult situations, serves all possible tactics, providing the opportunity for players to improvise and change their playstyle on the fly.

AI Behavior
In order to support the different playstyles, NPCs have different states which will adapt to every situation. Their behavior is very complex, but for the sake of simplification, let’s say that NPCs have 4 different states: relaxed, cautious, hostile, and alarmed.

  • Relaxed is when an AI character hasn’t seen the player, and is playing his default occupation.
  • Hostile is when an AI character has seen the player, knows where he is, and engages them in combat.
  • Alarmed is when the AI is actively looking for the player after he has disappeared, or an alarm has been triggered.
  • Cautious is when, after having seen the player or after an alarm has been triggered, the AI goes back to their regular occupation. This last behavior is very important, because it creates a gameplay loop where players can start playing stealth, get spotted, and enter a combat situation. It provides them with an opportunity to escape and wait for some kind of reset, then try to stealth their way back again during the same mission. Of course, the AI will be more careful, and the patrols will be a bit harder, but it will still be possible for players to get back on their feet and try another approach.
The AI has four different behavior patterns, each connected to how alarmed they are. However, even if players fail when taking a stealth approach, they can retreat at any time and come back later, allowing them to try again once the AI has ceased their search efforts.

Being a hybrid game, Deus Ex has to find the right balance between an AI that is challenging enough to engage you in great firefights, and providing players with enough latitude to be able to escape, or avoid being detected too easily. While combat is handled in a systemic manner, stealth is hand crafted by level designers. All relaxed and cautious patrols are custom made, and it is really important for us that players will be able to look at the patrols, understand them, and act accordingly. Patrol crea­tion is based on a lot of guidelines, designed to challenge the player without creating too much frustration.

As long as enemy characters are simply patrolling, players can easily go from cover to cover, relatively risk free. However, once the AI has been alarmed, are cautious, or are moving into a state of engagement, they will react more quickly and aggressively upon sighting the player.

The Use of Augmentations
Finally, in a game where augmentations are a major part of the story and players’ progression, we need to design the missions so that, when a player has the opportunity to use them, he will gain a strategic advantage over his enemies or his environment. Even if all missions can be completed without being augmented, every path and every corner is full of opportunities for players who decided to augment themselves. The main goal here is to create the need for the player to get augmentations, but also to give players opportunities to use the ones they already have. Because there is no way to know what augmentations players will have at any point in the game, we try to balance the missions by locking off different sections, requiring varying types of augmentations to access them, and making the »aug free« path a lot harder. Sometimes, some missions will rely heavily on one particular augmentation, but we keep tabs on the opportunities created by each aug, and make sure that one augmentation does not become more useful than another.


Player choice is at the center of every design decision regarding the quests, from high level objectives to minute to minute gameplay. For all that to happen, it requires an amazing amount of thinking and consistency, not only in terms of level design and narrative design, but also in terms of art. Deus Ex being set in reality, made the comprehension of the world a lot easier, helping to reinforce player choice. This is important because choices only truly exist in a game when you are able to understand, or be fully aware, of all the options available to you.


About the Author:

Julien Hantz
is Senior Level Designer at Eidos-Montréal.

Julien started his career as QA tester at Ubisoft in Paris in 2001, quickly switching to Level and Multiplayer Designer. In 2003, he moved to Ubisoft Montreal where he worked 5 years on a few AAA games as Level designer, Game designer, and Senior Technical Designer. With his expertise in stealth and non-linear gameplay he joined Eidos-Montreal to work exclusively on the Deus Ex franchise as Senior Level Designer. After a short stop at warner Bros. Montreal, which he joined in 2013, he returned to Eidos-Montreal in 2015 to help finish Deus Ex: Mankind Divided.