When Big Robot’s lead designer Jim Rossignol was coming up with the idea for the studio’s second game he was after a challenge. It wasn’t hard to find one. At that point, in 2014, Big Robot was comprised only of Rossignol and programmer Tom Betts. A game of any significant scale would surely test such a small team. 

And so it was: they started work on an open-world, first-person sci-fi shooter called The Signal from Tölva. The idea in the game is for players to trace a signal being broadcast from the planet Tölva. They do this by hacking into and remotely controlling the bots that roam the planet’s surface. As players explore the world for investigation sites, they have to survive a war between three opposing factions of robots, and collect resources to get better weapons and shields.

Big game, small team

To ease the workload, the pair of developers were able to lift some ideas from their 2013 debut, the first-person stealth and survival game Sir, You Are Being Hunted. The plan was to build upon the dynamic, AI-driven enemies that hunted the players so tenaciously in Sir. In particular, they wanted to double down on the “randomized, accidental conflict” that occurred between that game’s enemies.

“In Sir, most of the entities were on the same side. There was a sort of rolling fisticuffs timer between the hunters, so they could fall out and get into fights with each other, and they could accidentally shoot and anger a couple of the other entities. And so there was conflict between them but it was kinda incidental,” Rossignol says.

Emergent skirmishes between AI foes were a high point in Sir, You Are Being Hunted

“But it was also one of the most entertaining things. Like one of the best things was hunters bumping into a poacher in the woods, and the poacher firing its blunderbuss and screaming. That was really entertaining. So we said let's try and form around that bit in the next thing we do.”

The idea, then, was to increase the rate of those unplanned moments of chaos in Tölva. This required Big Robot to not only build an open world, but to fill it with enemies that would regularly encounter and fight each other. That’s a big task for just two people. To manage it, they took what Rossignol calls a “two-pronged approach” to the game’s development. 

Keeping it modular

“One [prong] was the awareness that we had limited time, limited resources, and that we needed to create something modular that was as efficient as possible and didn't require loads of assets,” Rossignol says. “The other was to make the world populated in a way that it was accessible to the robots so that it made physical sense that they would behave in certain ways the player was analogous with.”

Big Robot’s solution to overcoming the limited time and resources available was to make the player one of the robots, as opposed to a different entity altogether. This meant the player and the enemies shared the same equipment and weapons so that the number of individual assets the game required was kept to a minimum. 

“Instead of creating all these bespoke systems for bots, we said we're just gonna create a set of combat systems - weapons, AOEs, and shields - and then everyone gets them, whether the player or the robots, it's all encapsulated in the same thing,” Rossignol says.

As such, the player gets to choose a loadout, consisting of a primary and secondary weapon, a shield, and an Area of Effect attack. The robots are modeled on the same loadout system but are assigned their equipment randomly when they spawn. 

Another advantage of this design choice is that it made sense within the game's fiction for the different robots to behave similar to the player. They’re not just trying to survive, they’re also tracking the mysterious signal on this planet like the player is, and aim to find it before their opposition.

Stick to the mission

To engineer a sense of purpose within the robots a mission system was created that drives their AI. Throughout the game’s world there are bases, which any of the three factions can take over and control, allowing more of their robots to be spawned into the world. Rossignol explains that the AI-driven robots are spawned as a squad of four, with each squad member having a unique loadout, but all of them sharing the same mission.

“Sometimes it's a location, and they just go to that location, and patrol between two points and idle until something happens,” Rossignol says. “But in other cases it might be to travel to a specific location and scan and survey it. Quite often you'll see them having arrived at a crashed spaceship or a dead robot, they'll go round and put their scanners on it, and they'll hang around there just surveying, collecting data, and then they'll head off back to the base to get another mission and go and explore somewhere else.”

The player is given many of the same missions as the AI-driven robots which means they’re often sent to investigate the same hubs of interest. This makes it very likely that the player and the enemy robots will encounter each other and get into a fight. 

In the game’s best moments, it’ll be the case that not only has the player and an opposing faction intercepted each other, but a squad from the third faction has been sent to the same area too. This opens up the potential for the player to stand back and let the two factions go at it, and for them to also jump into exciting three-way firefights at their own peril.

Robots behaving badly  

It wasn’t enough for the enemy robots to simply encounter the player and try to kill them. What Big Robot soon learned is that having such a basic model to generate and guide its AI-driven bots gave way to homogenization. Firefights would get repetitive too quickly. 

To counteract this, while also keeping the bespoke work to a minimum, a bunch of unique behaviors were developed for each robot archetype. So a robot with a sniper rifle will hang back and shoot from a distance while another one armed with a short-range, high-damage beam weapon will charge in. 

But there are also behavioral variances within that so that even a squad whose members are all armed with the same weapon will display dynamism. “Some of them will choose to go down on one knee, some will just run in and fire, some will run into a certain point then start firing or they'll start firing and run again, some will fall back and come out again,” Rossignol says. 

“So you get that kind of ebb and flow depending on what weapon they've got. And then even guys who all have the same weapon in a particular squad will behave differently in terms of how they approach you.”

Feel the power

This was still not enough to solve all the issues Big Robot had to tackle as a result of their modular approach to enemy variation. What The Signal from Tölva was missing at that point was a sense of increasing difficulty as the player progressed through the game’s world. 

The solution was to introduce a ranking system. The player goes up through numbered ranks as they complete missions, which unlock new weapons and better shields. It would have been easy to keep enemy robots at the same rank as the player, so that they had access to better equipment when the player did, but that didn’t work for Big Robot’s approach.

“We didn't wanna lose the sense of 'I'm ranking up and getting considerably more powerful'. If you have a completely straight curve for that then the bots are getting tougher in the exact proportion to the amount of damage output you're getting, so then nothing changes,” Rossignol says. 

“So basically, within that, there are a large number of variants where the [enemy robots] have different ranks, up and down, so you will encounter weaker guys still, even though the higher level guys are starting to factor in. And by the end, you've got guys that are much tougher, but you also get guys that are a fair bit weaker, so you can spot those and take them out much quicker than you can the tougher guys.”

On top of that, there is the increasing aggression of the enemies in Tölva. Unlike in other shooters, once they spot a fleeing enemy, the AI-driven robots will go after them for as long as they remain in sight. And if they go into hiding behind some cover, then they will look behind the cover for them too. 

This is something that spilled over from Sir, You Are Being Hunted. With that game, Big Robot wanted the player to feel like they were constantly being hunted by an intelligent enemy. But it proved a little too tough for some players. 

To make it a little easier in Tölva, the player can command robots from their faction to come help them. It’s this that can lead to invigorating moments of revenge against an enemy squad that previously killed the player.

Map making

One of the reasons Big Robot spent so much time on engineering dynamism into the AI enemies of Tölva is due to a lesson they learned after watching people play Sir, You Are Being Hunted. What they discovered is that it was their systemic approach to enemies in Sir that created the most diversity in player experience. This went against what they had originally thought, which is that the procedural layout of the world would cause the most differences to each playthrough. 

With that new knowledge, Big Robot dropped the idea of having a procedurally generated environment, as with Sir, and decided to handcraft The Signal from Tölva’s world. The theory was that, by having control of the shape of the map, they could design spaces that would encourage the different robot factions to meet. It also meant that they could mold the flow and pace of the game’s open-world firefights with a proper sense of progression from one area to the next.

To manage all this, the pair created a real-time editor to use in Unity. “Typically, in Unity, you can't develop in real-time. You edit the scene, then you run it, and you run around inside to check it. We didn't wanna do that because we felt like having a player camera in the world to use to run around and test stuff straight away would be more efficient,” Rossignol says. 

“The approach we took instead was to create a system where we had a huge batch of props that are loaded into the scene. We then use a bespoke window that we created to pop them into a specific cell that the whole map is divided up into.”

The map generator in Sir, You Are Being Hunted worked by dividing the map into a grid of cells too. The difference was that Rossignol took the time to ensure each cell cohered with the one next to it rather than an algorithm. One of the biggest aspects he had to consider was how much open space there was in each cell versus the amount of cover available. 

“It was important to us that [the player and enemies] have cover locations everywhere that they can run to. One of the big tasks for me was making sure that, in any given area there was likely to be a fight, there would be some cover that looks naturalistic enough, but was actually a location that the robot knows it can run to and get out of the line of sight if it feels threatened or gets damaged, or just wants to fall back to reload or anything like that,” Rossignol says.

Era of the open-world shooter

The Signal from Tölva is far from the only shooter to deal with issues that occur when dividing up open spaces filled with autonomous enemies. It’s become a staple of the genre in recent years as the shooter has evolved from the tight corridors of games made in the 1990s to more open-world shooters like Far Cry, STALKER, and Destiny. 

Rossignol hoped that people would be more accepting of this looser approach to making a shooter due to familiarity with Tölva’s peers. But it was one of the things the game was criticized for in a couple of reviews. Specifically, the issue some reviewers had was that the enemy AI made dumb decisions during firefights, like running out of cover. 

“I think the flip side of [our design approach] is accepting that it's not a tightly-honed cover shooter. It doesn't have waist-high walls everywhere that people can mantle over and get behind,” Rossignol says. “We knew making a game this big, with this much dynamic AI content, with us being a tiny team ourselves, that that kind of intricacy in level design was just beyond us. So we had to create a whole bunch of systems environmentally and in the way the AI worked that meant that just didn't matter.”

Instead of precision engineering each firefight, what Rossignol did was tweak enemy spawn points and the physical structure of the world to encourage different types of firefights in certain areas. In the beginning parts of the game, for example, the player is stuck in a series of canyons so that firefights are contained. But the final areas of the game open up into big fields with lots of enemy spawn points. 

“Suddenly you have this situation where, just because of the nature of the space, it's much more likely they're going to see each other over a large distance. Or that they're going to be on a mission and hear something nearby and be able to get to it quickly because they're not caught in a canyon or at the edge of the map,” says Rossignol. 

“So as you get into that central area the level of danger and jeopardy goes through the roof because one of the main consequences of the way the systems are set up is that enemies are going to hear stuff that's happening and come and investigate.”

Think small

The final count of the team that worked on The Signal From Tölva is five. After six months, art director Olly Skillman-Wilson and Sir, You Are Being Hunted designer James Carey joined the crew. Then, in the final stretch of development, Dan Puzey was brought in as an additional programmer.

But the fact that it started off as a project that was manageable with only two is significant. Rossignol credits the restrictions that came with having such a small starting team with ultimately allowing them to develop the game in under three years.

It forced them to find a way to make an open-world game, while retaining the best bits of that format, without the resources available to the much larger teams that typically create them. “Keeping it tight and not going beyond those initial principles is basically what has allowed us to finish the game,” he says.