When Myth starts up, hold the space bar and click on NEW GAME. You now have access to every level but the secret one.

To skip to the next level, hold CTRL and press "+".

To enter the secret level, make your way to "The Sons of Myrgard" and kill all the ghouls in the caves. Once that's done, try to enter the caves. One of them will bring you to "A Long Awaited Party."

To make all footsoldiers stronger, including the enemy's, type "PizzaParty" while playing.