Enter the following codes at the Main Menu: 

destruct    Scorched Earth Game
enemy       Captured Enemy U-Fighter
engage      Super Tyrian mode
stealth     Ninja Fighter
stormwind   The Elemental Fighter
techno      Experimental Fighter
pretzel     Pretzel Pete ship
unknown     TX SilverCloud
weird       Carrot Food Fighter
nortshipz   Nort-Ship Z
lizard      Dragon ship

Enter the following codes during play: 

F2+F3+F6    Invincible   
F2+F6+F7    Level Skip  
F2+F3+F5    Destruction Mode
F2+F3+F10   Extra Money                                                     
TAB+1       Blue ship             
TAB+2       Red ship             
TAB+A       Souped-up red ship 

Christmas mode:
From the Start-Programs menu, select "MS-DOS Prompt." A DOSshell window will
appear. Change to the Tyrian 2000 folder. Type "file0001 yesxmas" and press the 'Y'
key when prompted. Certain items, weapons, ships and sound effects will be changed
to reflect the holiday spirit. The Christmas mode is date-activated and will only be
available until December 31, 1999.