Diehard Trilogy
Hit the ESC key to pause, hold down the R and 2 keys while entering the following combinations. Correctly entering codes unpauses the game

Die Hard 1
RIGHT, UP, DOWN, E	grants invincibility.
RIGHT, E, DOWN, O	gives fifty grenades and fifty smokebombs.
RIGHT, UP, DOWN, DOWN, E, RIGHT	gives guns (repeat for different selection).
Die Hard 2
RIGHT, UP, DOWN, E	gives guns.
RIGHT, E, LEFT, O, A, DOWN, E	gives missles and grenades.
Die Hard 3
LEFT, O, UP, DOWN, E, RIGHT	gives infinite lives.