Big Cheat:
Enter your name as SWIV!AndLetDie. Make sure that you type it exactly as this cheat is case-sensitive. When you go to the main menu, there will be a new option. Click on this to select your level, and while in the game, press F12 to bring up a menu where you can choose which weapons you want.

Thanks to Revolution readers Peter Bloomfield and Hanro Roos!