The following are known Game Genie Codes for Phantom 2040 on SEGA Game Gear.

• Start With 10 Bullets For Your Normal Gun
  109-309-A2A
• Start With 25 Bullets For Your Normal Gun
  259-309-A2A
• Start With 50 Bullets For Your Normal Gun
  509-309-A2A
• Start With 75 Bullets For Your Normal Gun
  759-309-A2A
• Start With 99 Bullets For Your Normal Gun
  999-309-A2A
• Infinite Bullets For Your Normal Gun
  005-A9E-E6E
• Start With 1 Life
  019-419-E66
• Start With 5 Lives
  059-419-E66
• Start With 7 Lives
  079-419-E66
• Start With 9 Lives
  099-419-E66
• Always Collect Max Bullets For Your Normal Gun
  993-2AC-F72
• Almost Infinite Energy
  7EE-509-3B7
  Note: You may have to turn this off in order to kill some enemies.