Regain Health: Up + Up + Down + Down + Left + Right + Left + Right + Circle + X.
Regain Ammo: Triangle + Circle + X + Square + R1 + Triangle + Square + X + Circle + R1.
Acquire All Levels: Input the following code while playing the game: Left + Left + Left + Left + L1 + Right + Right + Right + Right + R1.
Acquire All Levels (Half-Life 2): Input the button sequence on any level while playing: Left + Left + Left + Left + L1 + Right + Right + Right + Right + R1.
