From the file's introduction: Vanguard Spaceships is a set of rules for spaceship design and spaceship combat intended both to serve as a stand-alone tactical spaceship combat game and to serve as a supplement to the Vanguard science-fiction roleplaying game. As a game of hard science fiction, it includes speculative but plausible technology. Spaceships are propelled with reaction drives, not inertialess drives. If crews need simulated gravity then they spin the ship or accelerate hard; they don?t have artificial gravity. To destroy an enemy, they fire lasers, missiles, or kinetic-energy projectiles. To survive combat, they usually must avoid being hit, since there are no shields. This is not a prediction of what the future will hold, but it is a representation of something that is a remote possibility.