Some "flight models" use a physics system based on Newtonian physics, but these are usually limited to maneuvering the craft in its direct environment, and do not take into consideration the orbital calculations that would make such a game a simulator.
Many of the pseudo simulators feature faster than light travel.
Others focus on gameplay rather than simulating space flight in all its facets.
The realism of the latter games is limited to what the game designer deems to be appropriate for the gameplay, instead of focusing on the realism of moving the spacecraft in space.
The reward for the player is on mastering real or realistic spacecraft, celestial mechanics and astronautics.
Realistic space simulators seek to represent a vessel's behaviour under the influence of the Laws of Physics.
As such, the player normally concentrates on following checklists or planning tasks.
Piloting is generally limited to dockings, landings or orbital maneuvers.
If the definition is expanded to include decision making and planning, then Buzz Aldrin's Race Into Space (1992) is also notable for historical accuracy and detail.
On this game the player takes the role of Administrator of NASA or Head of the Soviet Space Program with the ultimate goal of being the first side to conduct a successful manned moon landing.