10 years on, ‘Kerbal Space Program’ shoots for more distant stars

It seems fairly unanimous among Kerbal Space Program‘s development team, Squad, that, given the opportunity, they’d definitely go to space.

“It’s the one great exploration frontier that still remains, right?” said co-lead engineer David Tregoning in an interview with Mashable. There are still many mysteries hidden in our oceans of course, but that prospect simply isn’t as exciting for Squad as the pull of deep space. “You are talking to space nerds here.”

It makes sense considering that spacefaring is what Kerbal Space Program is all about. Released on June 24, 2011, the sandbox game lets players build spacecraft and launch enthusiastic green creatures called Kerbals into space — often with more failures than successes. What sets Kerbal Space Program apart is that it’s heavily based in science fact rather than science fiction, using a physics simulation that’s as realistic as its developers can manage with only the power of a home computer.

This commitment to realism has garnered Kerbal Space Program a dedicated fanbase of virtual astronaut, whose fascination with space has been nurtured by the game’s basis in relative reality — actual physics and actual science. Many are still playing Kerbal Space Program 10 years later as they anticipate the sequel’s release, including Tregoning and fellow co-lead engineer Jamie Leighton, who both began as fans.

Kerbal Space Program was intended to entertain space nerds, but it’s also creating them.
Credit: KERBAL Space Program: EnhaNCED Edition

Happy accidents

“It gives you the opportunity to try and do stuff that real space programs do,” said Tregoning. “So the community that it gathers, it really is heavily laden with people who are interested in space exploration, physics, all that kind of scientific endeavor.”

As Leighton noted, it also works the other way around. “We’ve had plenty of examples of people in the community who, from the game, it’s grown their passion for space and astrophysics, to the point where they’ve actually gone and studied it and now work for NASA or ESA.”

In fact, Squad worked with scientists from the European Space Agency to introduce actual missions to Kerbal Space Program. In 2020, the studio released the free update “Shared Horizons”, which allows players to build the Ariane 5 launch vehicle and play through two scenarios based on real ESA missions — BepiColombo, a mission to Mercury carried out in partnership with the Japan Aerospace Exploration Agency; and Rosetta, a mission to land on Comet 67P/Churyumov-Gerasimenko.

“I would say education was a happy accident for us,” said Nestor Gomez, Kerbal Space Program‘s lead producer. “What the team in the early days was trying to achieve was just doing a fun game that could entertain space nerds. But they ended up implementing a very good simulation.”

Kerbal Space Program
Credit: Take-Two Interactive

Kerbal Space Program has since been adapted for use in classrooms to teach students science and physics — a mission that Squad hopes to continue.

“Now…education is something that we actually are looking into, because we’ve realised how powerful the game is for that,” Gomez continued. “I think [Kerbal Space Program] is a great example of how you can actually teach someone by just letting them experiment and try again, and try until they achieve something.”

Constant, repeated failure admittedly doesn’t sound fun. However, the humour of the cheery Kerbals softens the blow, and the feeling of accomplishment after conquering a challenge spurs players to keep trying.

“I think it’s just the sense of achievement,” said Leighton “They start off simple, thinking, ‘I can get this rocket into space.’ And then they realize it’s not that simple. And after many crashes, which are always humorous… they get to space and they go, ‘now can I make it to the moon?'”

2 Kerbal 2 Space

Though dedicated players are still shooting off rockets a decade after Kerbal Space Program’s launch, the developers are ready to press on toward more distant stars. Update 1.2 on June 24 will be the last big addition to the original game, after which the team will move on to work on the sequel: Kerbal Space Program 2.

“It still kind of makes me wonder if I’m living in a simulation, or this is a Truman Show kind of thing, because the one game with which I have been obsessed for a very long time turned out to be this, the thing I got an opportunity to help build,” said Nate Simpson, creative director for Kerbal Space Program 2 at Intercept Games.

Simpson had already played the original game for over 2,000 hours when he first heard a sequel was being discussed. Now his team at Intercept is working side by side with Squad, the latter updating and maintaining Kerbal Space Program while the former gets a “head start” on its successor.

“There has been a need for both products to exist in parallel, because we don’t want to leave the community in a position where they’re just kind of holding the bag,” said Simpson. “We want there to be something interesting coming out all the time.”

Credit: Kerbal Space Program: Breaking Ground

It’s reasonable that fans might be apprehensive about a Kerbal Space Program sequel from a different studio. However, Simpson noted that Squad is already providing input into development and has been very detail-oriented and protective of its legacy — right down to how cute the Kerbals should be.

“The original Kerbals have drastically asymmetrical eyes, and initially our Kerbals had the same size eyes,” said Simpson. “And they were like, ‘That’s not a Kerbal, the eyes have to be wonky.’ So we hashed it out, and now we have wonky eyes too.”

We have liftoff

While Kerbal Space Program 2 will add new features such as multiplayer, the “quality of life” improvements will likely be the most immediately apparent. One of the main focuses is an overhaul of the first time user experience, so new players don’t simply bounce off space travel and go back to capping each other in Fortnite.

This doesn’t mean launching your Kerbals into the sky will be any easier, though. Rather, the retooling is targeted at the game’s tutorial, guiding users visually with animations and making the whole process more interactive.

“So what we’ve discovered is that there are forms of failure that are constructive and enjoyable,” said Simpson. “That’s a big part of why Kerbals are part of this at all, is that they turn a failure that would otherwise be a fairly tragic event into something that’s cause for laughter…. So teaching constructive failure is a really big part of what we’re trying to do with that first time user experience.”

Kerbal Space Program 2 has also added a big button players can push to launch their rocket instead of relying on a hotkey to get the job done, aiming to make launches feel more satisfying. It’s a simple addition, but one Simpson believes “will have a huge impact on people’s ability to get into the game.”

Kerbal Space Program 2’s multiplayer will have the same “demolition derby” sensibilities as singleplayer.
Credit: Kerbal Space Program 2

Racing reality

Despite fun additions like the launch button, Kerbal Space Program 2 remains focused on authenticity, and the developers are consulting with experts to ensure everything is grounded in real science, physics, and engineering. Still, some liberties have to be taken, not only for the sake of entertainment, but due to the limitations of reality.

Like its predecessor, Kerbal Space Program 2 starts with largely current day rocket technology, having players develop the same engines that they did in the first — albeit with some visual upgrades. However, as players proceed through Kerbal Space Program 2, they soon unlock new technologies which are markedly less familiar both in-game and out.

These range from banned technologies such as nuclear pulse propulsion, to theoretical ones such as interstellar flight and interplanetary colonisation.

“Our game takes the step of moving our tech tree into the near future, so we’re necessarily getting into some more speculative technologies as well,” said Simpson. “There’s a lot of new stuff, new technologies, many of which have never been envisioned by anyone. Frequently we’ll come to a subject matter expert and we’re talking about a particular kind of propulsion or a particular kind of engine, and there literally has never been a drawing of one before.”

A particular example he gives is metallic hydrogen propulsion — a theoretical propellant that isn’t yet possible using today’s technology. This portion of the game’s tech tree splits into two branches, each following alternate possible ways the technology could develop. The developers also had to design their own rockets, consulting with experts and working iteratively through ideas until they were satisfied it was plausible.

“Metallic hydrogen is a speculative state of hydrogen that is possible under extreme pressures,” said Simpson. “If stable metallic hydrogen could be stored at room temperature it would completely revolutionise rocketry. But what a metallic hydrogen rocket would actually look like is a matter of some speculation.”

Some of the rocket parts will be familiar and some won’t, but all will get a graphics upgrade.
Credit: Kerbal Space Program 2

Yet while theoretical future technologies have caused challenges for the Kerbal Space Program 2‘s team, the rapid development of current space technologies has also had the development teams struggling to keep up.

“We’re in a weird historical moment where human spaceflight is progressing at a seemingly exponential rate, which in my lifetime is completely unprecedented,” said Simpson. “SpaceX in particular, of course, is driving us nuts, because they come up with new ideas every three days.”

Fortunately for Elon Musk fans, Intercept plans to make Kerbal Space Project 2 a long term mission, just like the first game. This will involve ongoing updates, including adding parts and technologies that didn’t make it in at launch. So while reusable rockets and other technologies headlining the news aren’t included yet, the aim is that they will be eventually.

Whole new worlds

The inclusion of interstellar travel necessitates the creation of multiple star systems and planets. However, not all of them will be as hospitable as the Kerbals’ home planet of Kerbin, or as easy to access.

“We hold ourselves to the standard that every new celestial body needs to require the creation of a new kind of vehicle to land on it, to access its resources, to fully explore it,” said Simpson. “We can’t just make things farther and farther away and bigger and bigger, that’s sort of monotonous. So while there are some interesting gravity challenges associated with some of our new celestial bodies, we’ve tried to be a little more clever about, ‘Oh, now I gotta solve this problem a new way.'”

Travelling to different star systems creates a whole new set of challenges.
Credit: Kerbal Space Program 2

Kerbal Space Program focused mainly on issues of velocity and gravity, however the sequel throws in matters such as the composition of planets and the frost line (that is, how far a planet can be from a star before ice can begin to form). The development team also checks any new celestial bodies they create with an astrophysicist in order to ensure each creation remains within the realm of reality.

“In the early going, we were really worried that we were getting too weird with it,” said Simpson. “If anything, we were not being ambitious enough in our celestial body design…. We’re trying to stay in a universe of plausibility, but also discovering that we can do some pretty weird stuff even within those guardrails.”

After you’ve successfully landed on a planet you’ll have to find and collect resources to build vehicle parts and expand your colony. However, this doesn’t mean Kerbal is pivoting to become a resource management game. Once you’ve picked up a resource, brought it to your colony, and built some transport infrastructure, an automated delivery system will continue to deliver it. For Simpson it’s a “happy medium” between giving players new challenges to overcome and letting them get back to the business of spaceflight.

Simpson noted that, while you can colonise other planets, you won’t have to worry about feeding your Kerbals and keeping them alive once you get there. Life support isn’t going to be a concern.

“In the end it’s a game about making and flying rockets, and if you have to worry about arriving at a place with a rocket full of tiny green corpses that actually does remove some of the fun,” said Simpson.

Don’t worry about the Kerbals — they’re just happy to be here.
Credit: Kerbal Space Program 2

Kerbal Space Program isn’t a perfect physics simulator, and it doesn’t claim to be. Still, it’s as close as the layperson is likely to get for now — at least until the sequel arrives.

“If you look at a real space program run by someone like NASA, they have rooms upon rooms of computing power, and they use that for realistic physics,” said Tregoning. “We’re limited to a desktop PC…. And so it’s [about] keeping that pillar of a realistic physics simulation, as well as making it fun. So what parts can we add? What things can we add, what humor can we add to those sorts of situations?”