For gamers interested in realistic spaceflight there are plenty of options. Games like Kerbal Space Program and Juno: New Origins offer an engaging experience building and flying rockets (and non-rocket machines). So why make Orbit One? There are a few differences:

1. Exploration set in our solar system.

2. Quicker and easier rocket design and maneuver execution.

3. More realistic orbital mechanics.

Let's break down how Orbit One approaches each point.

Existing games are mostly set in fictitious solar systems. This is a sensible design choice, as it allows game developers to provide a smoother difficulty curve. Starting with orbiting the home planet and visiting increasingly difficult moons and planets, each of which can be imbued with its own characteristics.

While this approach does make for good gameplay, it comes at the cost of realism. For players interested in a more realistic, grounded experience, Orbit One is set in our solar system. Surfaces of planets and moons are based on real imagery*. In some cases, the roughness of planets and moons is also known.

*Only the southern hemisphere of the moons of Uranus and Neptune have been photographed, so the northern halves of these moons is fictitious.

If you're like me, you've spent a lot of time building rockets by snapping together pieces, adjusting symmetries, and defining staging plans. You have also spent a lot of time waiting for a launch or maneuver to complete, and have perhaps turned to mods to automate these processes. A Lego-like building experience is a lot of fun, and manually flying your creations is very rewarding (even, or especially, when they explode).

That being said, successful rocket designs do follow a similar pattern of stacked stages and possibly boosters. Launches typically follow the same pattern (1: go up; 2: go sideways). Maneuvers are mostly an exercise of pointing in the right direction and firing engines at the right time. Is it necessary to do these things by hand?

In Orbit One these systems are simplified and automated. Creating a rocket is a few simple steps, although finding the right design is still challenging. Launches, landings, and maneuvers are all automated. Even docking is automatic, but it's still up to you to get close enough and match speeds. All of these changes make it easier to manage multiple vehicles and focus on their overall operations, without getting bogged down in details.

Every space sim game advertises realistic orbital mechanics, but what does that mean?

The typical way of simulating orbital mechanics in games is by using a series of equations to represent an object's orbit around a single body (moon, planet, sun). These "2-body" equations allow the object's position to be predicted at any point in the future, which is a huge win for performance. But there are more than two objects in the solar system: every planet and moon, as well as the sun, is exerting gravitational influence on a spacecraft in flight, and the position predicted by the equations doesn't factor in these influences.

This simplification appears in two main ways. First, orbits in real life are generally less stable than the 2-body equations would suggest. For example, low orbits around the Moon are unstable except at a few specific inclinations, and satellites around the Moon will require occasional maneuvers to maintain their orbit. Second, there are specific locations created by the influence of multiple gravity sources where an object can "park" and remain stationary indefinitely. These points, called "Lagrange points", are occasionally useful for scientific purposes: the James Web Space Telescope is placed at Earth's L2 Lagrange point because it is permanently in Earth's shadow.

Orbit One uses the 2-body equations to display projected orbital tracks. But when it simulates the actual movement of vehicles, Orbit One calculates the gravitational influence of the sun, planets, and moons to determine the new position. This enables the simulation of unstable orbits and Lagrange points.

When performing an N-body simulation, performance is a major consideration. Orbit One simulates movement with one second time steps. There are 86,400 seconds in a day and about 2,592,000 seconds in a month, each of which represents a computation involving nearly 30 gravitational objects for each vehicle. For this reason, performance has been a major design consideration for Orbit One, with the objective of simulating at least half a game-day per second on slow processors, and at least one full game-day per second on faster processors.

Orbit One builds on the principles of its predecessors to offer a different take on the realistic space sim. Rather than being vehicle-oriented, Orbit One puts the focus on navigating in space by simplifying some of the routine rocket-building and operating tasks. Once in space, it enhances the experience with more accurate physics to provide a unique challenge.