The flight model is arcade-style as opposed to realistic, as the game features no inertia; the spacecraft banks like an aircraft to turn, in air, outer space, and underground; and it is possible to hover.
The construction of the shield generators and the space station itself progresses continuously over the course of the game, and failure to destroy the space station before construction was complete will result in loss of the game (the space station would be used to destroy the player's home planet).