The following are known Game Genie Codes for Phantasy Star II on SEGA Genesis.

Note: You cannot save the game when using Game Genie Codes when playing on a cartridge.
• ATBA-AA4R
  Master Code – May only necessary if you have a newer model Genesis.
• BXJA-AA26
  Everything is free
• RG8A-A60R
  Everything at the armor store is free
• RG9T-A60J
  Everything at the tool shop is free
• RG7T-A6V2
  Everything at the armorer’s store is free
• AL6T-AA50
  All medical care is free
• AL5T-AA76
  All clones are free
• AMFT-AA4G
  All teleporting is free
• CJZT-AA2N
  No hp taken off from physical strikes
• CJ0A-AA2Y
  No hp taken from venom strikes
• CV2T-AA5R
  No hp lost in damage zones
• BXCA-AA2L
  Do all peaceful magic regardless of TP (TP points are deducted)
• RGZA-A6XL
  Do all peaceful magic if you have enough TP (TP is not deducted)
• CTWT-AA3L
  Battle magic does not use up your TP
• AJOT-AA4W
  Players never get paralyzed
• REYA-A6TY
  All enemies die in one strike
• KAYA-AS2R + GJYA-AAC8
  Your regular attacks are more powerful
• KAYA-AM2R + BAYA-AAC8
  Your regular attacks are much more powerful
• GIYA-AACJ
  All battle magic is 2x more powerful
• G2YA-AACJ
  All battle magic is 4x more powerful
• FCYA-ACCJ
  All battle magic is 1/2x as powerful
• L2YA-AECJ
  All battle magic is 1/4x as powerful