Display score:
Before Demonstration mode starts press Left Gun Trigger(2), Right Gun Trigger(3), Left Gun Trigger, Right Gun Trigger, 'Start' and if you have entered the code correctly your score will appear in the corner.

Unlock More Lives:
Repeatedly tap 'Start' quickly when you insert your coins before a game play or during a 'Continue'.

Unlock Bad Ending:
Complete the game with a score less than 80,000 points and with the last numeral as a zero.

Unlock Normal Ending:
Complete the game with a score less than 80,000 points and with the last numeral other than zero.

Unlock Good Ending:
Complete the game with a score more than 80,000 points.

No Reloads against Emperor:
Just before fighting the Emperor shoot off-screen 5 times to avoid having to reload during the battle.

Hidden room:
To access this room which has bonus lives and points you must reach the Emperor Boss at the top of the building without killing any civilians or allowing any civilians to be killed.