Play as Optimus Prime Generation 1 version:
     Press  Up(2),  Down(2), Right(3) at the "New Game" main menu. The
screen  will  flash  to  confirm correct code entry. Select the "Bonus
Features"  option  then  the  "Generation  1"  option  to  use the new
appearance.

Play as Starscream Generation 1 version:
     Press  Right,  Down,  Left(2), Down, Up(2) at the "New Game" main
menu.  The screen will flash to confirm correct code entry. Select the
"Bonus  Features" option then the "Generation 1" option to use the new
appearance.

Play as Jazz Generation 1 version:
     Press  Left,  Up(2), Down, Left, Up, Right at the "New Game" main
menu.  The screen will flash to confirm correct code entry. Select the
"Bonus  Features" option then the "Generation 1" option to use the new
appearance.

Bonus Cybertron missions:
     Press  Right,  Up(2),  Down,  Right, Left(2) at the main menu and
start  through  replay  missions.  The  screen  will  flash to confirm
correct code entry.

Generation 1 Megatron:
     Collect all the Transformer Shields in the Decepticon story line.

Generation 1 Optimus Prime (cartoon model):
     Collect all the Autobot Faction Symbols in the Autobot story line.

Generation 1 Robo-vision Optimus Prime:
     Successfully complete the Autobot story line.