The following are known Game Genie Codes for Defender of the Crown on Nintendo Entertainment System (NES).

• Only 10 Soldiers In Your Garrison
  ZAVVALGO
• 40 Soldiers In Your Garrison
  AZVVALGO
• Soldiers For Free
  AAEOUPPA0
• Triple The Cost Of Soldiers
  LAEOUPPA
• Halve The Cost Of Knights
  GAEOKOAA
• Double The Cost Of Knights
  APEOKOAA
• Halve The Cost Of Catapults
  YAEOSOYA
• Halve The Cost Of Castles
  ZAEOVPGO
• 255 Soldiers In Your Garrison
  NYVVALGO
• Knights Cost Nothing
  AAEOKOAA
• Catapults Cost Nothing
  AAEOSOYA
• Castles Cost Nothing
  AAEOVPGP