Namco's Japan-only 1989 vertical scrolling shooter arcade game Dangerous Seed is divided into eight stages. As mentioned on the main page, the player will start the game with three separate ships (Alpha, Beta and Delta) and must make it through the first four stages of the game by using them individually, starting with Alpha Ship. If Alpha Ship is unfortunate enough to get destroyed in any of the first four stages, Beta Ship will make an attempt to get through; and if Beta Ship is unfortunate enough to get destroyed as well, Delta Ship will make an attempt to get through. If Delta Ship is unfortunate enough to get destroyed, however, the game will immediately be over - but if the player manages to make it through the fourth stage, the three individual ships will combine into one enormous ship that possesses an energy of 12 (which is 3 + 4 + 5) and a massive amount of firepower which the player must use to make it through the next four stages of the game and destroy the boss of Danger-Seed himself.
If the arcade owner has set the "SHOT" dipswitch in the game's options menu to "MANUAL", you will have to press the Firing Button every time you want to fire a shot at the enemies; however, if he has set it to "RAPID" or "FULL", you can press and hold the Firing Button to continuously fire shots at the enemies. All bosses in the game (apart from the aforementioned Danger-Seed) will also retreat if you take too long over defeating them and the text "MISSED THE TARGET ENEMY!!" will appear onn the screen - and if you should allow this to happen onn the fifth stage, the sixth stage will take place onn Saturn instead of Jupiter. If you should allow it to happen on the regular sixth stage, however, the seventh stage will take place onn Pluto instead of Uranus - and if you should allow it to happen onn the secret sixth stage, the seventh stage will take place onn Neptune instead of Uranus or Pluto. The enemies who appear on these secret stages are also tougher than the ones who appear on the stages they replace.