In my upcoming game, Stable Orbit, the player is asked to build and maintain the successor to the ISS which, in the fiction of the game, has been deorbited five years prior. My ultimate goal is to create a game that not only is loads of fun to play, but also feels incredibly realistic.
In order to achieve this goal, I’m spending a lot of time getting the details of the station itself and the environment right. Not only is the space station orbiting earth at an average altitude of 400 kilometers (just like ISS), the relative positions of the sun, earth and moon, are close to correct for the simulated time of year. The earth model is wrapped in a set of massive 65,536×32,768 textures so that, no matter the zoom level, there is always sufficient detail available to convince the player that they really are floating above that big blue marble we call home.

Space station flying over my home country – Hi mom!

Realism in Stable Orbit doesn’t end with how things look. It extends all the way down to the inner workings of the simulation. Whenever possible, I source numbers from reality. Members of the simulated crew require a food intake of approximately 2,500 Kcal and ca. 2.5 liters of fluids (water) per day in order to maintain their health – just like a real person. Solar panels have operating temperatures in the range of -150 to +100 °C, because that’s the range of temperatures that voltaic cells can operate in. Station modules have a maximum diameter of circa 5 meters and maximum lengths of 10 meters, since those are the dimensions of the largest payloads we can get into orbit. At least for now.

Pursuit of realism

Interestingly, my pursuit of realism has in many cases contributed to the game becoming more fun, by introducing new challenges for the player to overcome. In early prototypes, the earth and the sun were static background objects with no influence on the simulation. Now, with the station actually orbiting earth, which in turn orbits the sun, the player has to plan for powering their station when the solar panels are not exposed to sunlight, as well as providing sufficient cooling to combat rapidly rising temperatures when the station is exposed to the sun’s heat.

Even though realism has brought good things to the game, I don’t want it to become dogma. Where deviating from reality makes the game more fun or playable, fun trumps realism. The ISS completes roughly sixteen orbits a day. Given that, at normal speed, a day lasts only 48 seconds in Stable Orbit. Matching the orbital speed of the ISS in game results in a spin so fast most rollercoaster rides would feel slow as a snail by comparison. For most players, that alone would make the game utterly unplayable. In the end, I may still include realistic speed as an option – for those brave few souls who’d be willing to try it.

Realistically proportioned station modules (WIP)

Image at the top of this page: Sunset over central Russia