Every technology, from the Nuclear Thermal Rockets, to the Solid State Lasers, to the Magnetoplasmadynamic Thrusters, was implemented using actual equations from Engineering and Physics textbooks and white papers. Everything aspect of these systems, from the efficiency, to the size and mass, to power usage, are all derived from equations, not estimated or faked.
With an N-Body Simulator (the kind NASA uses to plot actual spacecraft trajectories), all orbital phenomenon from hyperbolic orbits, Lagrange points, and orbital perturbation are all correctly simulated. Spacecrafts can stationkeep orbits, or enter into free falling perturbed orbits.
Assume the role of an admiral and fight through a detailed storyline chronicling the descent of the solar system into all out war, spanning every planet in the solar system and everything in between. Or simply play in the sandbox, designing ships and pitting them against other ships.
The solar system is modeled completely to scale. The sizes of all planets, moons, and asteroids are accurately enormous, and the distance between them is similarly mindboggling huge. Gravitational attraction is precisely modeled, and the extremely high orbital speed of your ships that results around low orbit of large celestial bodies is correspondingly correct.
Build your spacecrafts out of rockets, propellant tanks, weapons, powerplants, radiators, and crew modules. Wrap it all up with multiple armor layers, and maybe a Whipple Shield to boot. The acceleration, moment of inertia, delta-v, and much more are all correctly calculated for all spacecrafts you design.
Tweak everything from the nozzle length or stoichiometric mixture ratio of your bipropellant rockets to the armature and rail dimensions of your railguns. Every change you make is backed by real life equations, and you can the see the results in real time, from the change in your rocket's exhaust velocity, to your railgun's inductance or muzzle velocity.
All materials, chemical reactions, and spectra are physically correct. When your arclamp pumps your solid state laser, the pumping bands are going to have to match up with the actual emission spectra of your excitation gas. When the photon absorption of a material is needed, it is derived from actual refractive index spectra data.
The engine supports black box creation of untested or far future technology for modders to work with. All other game data, from levels to material properties, is also accessible to modders.