Now I have recently made a password system

(i'm so proud of myself) But i have though about it hard and said all someone has to do is tell the person the password and he can win the game in a blink of the eye. Now I want to know if there is anyway to keep the person from skipping. 1 Thing i was thinking about doing was making the heros have upgrades and every time you get to a different area they will up grade that unit. So if they do skip they will most likely die.
But I have no idea how to make the computer units stronger.
The Map is atttched if you wana see it.