Enter the options menu and highlight "Password". Then, hold Select and press Triangle, L1, Square. Release Select and press Triangle, L1, Square, Triangle, L1, Square. Choose the desired level in the "Round=" box that appears on the screen by pressing Left or Right.
Ten continues, planes and plasma shots
Pause the game and select "Options". Then, press Triangle, Square, Circle, Square, Triangle, Square, L1, L1 + R1, Select(2). If you entered the code correctly, there will be a skull picture and sound. Quickly press Triangle, Square, L1(2), Square, Triangle. The game will restart with ten continues, planes, and plasma shots.