For its time, it was incredibly complex. You had to manage shields, weapons, propulsion, targeting computer, energy level and navigation while keeping an eye on the galactic chart to make sure your starbases weren't under attack. If you were hit, either by enemy weapons fire or crashing into an asteroid, you could suffer damage to any of your ship's systems and would have to choose between continuing to fight or fleeing to a starbase for repairs.
Star Raiders was available for several other Atari systems, but the 400/800 had the best graphics and gameplay, and made extensive use of the keyboard.
It's hard to believe the entire game fit into 8 Kilobytes of ROM.