Notes:Raiden Trad (Genesis)

Options
The programming for setting the difficulty in options is located at. It allows only three settings: - EASY,  - NORMAL, and  - HARD. There's nothing to suggest a - FREE setting.

controller check 00:0848 08 00  BTST    #2,D0              //check d-pad left 00:084C 67 10  BEQ     #$10 [00:085E]     //goto 00085E if not pressed

d-pad left pressed 00:084E 53 39  SUBQ.B  #1,($00FFC026)     //lower difficulty setting 00:0854 6A 26  BPL     #$26 [00:087C]     //goto 00087C exit if difficulty is not on EASY

rollover, set HARD difficulty 00:0856 13 FC  MOVE.b  #$02,($00FFC026)   //HARD

controller check 00:085E 08 00  BTST    #3,D0              //check d-pad right 00:0862 67 18  BEQ     #$18 [00:087C]     //goto 00087C if not pressed

d-pad right pressed 00:0864 52 39  ADDQ.B  #1,($00FFC026)     //raise difficulty setting 00:086A 0C 39  CMPI.B  #$02,($00FFC026)   //check if difficulty is HARD 00:0872 6F 08  BLE     #$08 [00:087C]     //goto 00087C if difficulty is not on HARD

rollover, set EASY difficulty 00:0874 13 FC  MOVE.b  #$00,($00FFC026)   //EASY

exit 00:087C 4E 75  RTS

Gameplay
In game, is checked for.

00:2C90 12 39  MOVE.b  ($00FFC026),D1 00:2C96 C2 3C  AND.B   #$03,D1 00:2C9A B2 3C  CMP.B   #$03,D1 00:2C9E 66 04  BNE     #$04 [00:2CA4] 00:2CA0 12 3C  MOVE.b  #$02,D1            // ??? effect 00:2CA4 E4 19  ROR.B   #2,D1 00:2CA6 80 01  OR.B    D1,D0 00:2CA8 13 C0  MOVE.b  D0,($00FFE9AF) 00:2CAE 53 79  SUBQ.W  #1,($00FFE99A) 00:2CB4 66 06  BNE     #$06 [00:2CBC]