First press [Alt] + [F12] to bring up the entry screen.
Now type in wlrnwhdakf or doomsday to enable the cheat mode.
You should see the phrase 'Cheatcode Enable' appear.
Now press [Alt] + [F12] then [Enter] and type one of the
Enable one hit kills - onekill on
Disable one hit kills - onekill off
More money - money <1 - 999>
Stop timer - time off
Enable timer - again time on
Invincibility - invulnerable on
Disable invincibility - invulnerable off
Adjust character's intelligence - int <1 - 999>
Adjust character's dexterity - dex <1 - 999>
Adjust character's damage strength - hit <1 - 999>
Adjust character's strength str - <1 - 999>