Excalibur Ship
Hold Select and press: Triangle, Circle (2), Triangle, Square, Circle, Square
when 'Press Start' appears at the title screen.
Original Asteroids Game
Begin the game on mission 1 and reach level 15. Next, shoot the green vector
graphics asteroid that appears, then complete the level. Save the game at this
point to keep the original version of the game unlocked.
Classic Asteroids
On the "Press Start" screen, hold down the Select button, and (while holding it
down) press circle, circle, circle, triangle, square, square, circle.
You'll hear a slight asteroid explosion sound. When you press Start, there will
be an extra option on the Main Menu screen.... Classic Asteroids.