Log on with the name Viper to enable cheat mode. You will be able select any mission. Type in these codes during game play:

ALT+I - Invincibility
ALT+L - Full ammo
ALT+A - View all targets
ALT+Q - Real/arcade flight toggle
ALT+R - Disable damage mode
ALT+X - Crash Viper
ALT+K - Disable smoke trails
ALT+J - Show framerate