Namco Museum Volume 1 Cheats (PlayStation)

In the first stage, do not shoot at the ships as they go into their formation. Once all
the ships are in formation, isolate the first two (yellow/blue bees) on the left side.
They are in the first column of bees on the left side. Kill all the other ships except
these two bees. After all the other ships are gone, allow the two bees fly and shoot at
you for the next 10-20 minutes. Do not shoot during this time. After some time, both bees
will stop shooting. Allow the bees to finish 3 to 5 more passes, then kill them. From this
point on, ships in the game will no longer shoot.
 

Game Shark Codes

To prevent the aliens from returning fire, allow all of the aliens to appear on the screen
before you fire a shot a them, then shoot all of them apart from the first two
(yellow/blue colour) on the left hand side of the screen. Put the kettle on and make a
cup of coffee while the two remaining ships are left to fly around for fifteen minutes.
When you are certain that they have stopped firing at you then shoot them. All other
aliens will now refrain from firing back at you for the rest of the game.