Some final code requests (and screenshots)

[Subtraction]

Code:

C2/566E: E0 44 00     CPX #$0044     (are we pointing at Step Mine's menu slot?)
C2/5671: D0 09        BNE $567C      (branch if not)
C2/5673: AD 64 18     LDA $1864      (minutes portion of time played, from when main
                                      menu was last visited.  or seconds remaining,
                                      if we're in a timed area.)
C2/5676: C9 1E        CMP #$1E       (set Carry if >= 30 minutes)
C2/5678: AD 63 18     LDA $1863      (hours portion of time played, from when main
                                      menu was last visited.  or minutes remaining,
                                      if we're in a timed area.)
C2/567B: 2A           ROL            (MP Cost = [hours * 2] + [minutes DIV 30] or
                                      unintended [minutes remaining * 2] +
                                      [seconds remaining DIV 30])

If you want to halve the MP cost, replace the ROL with a NOP. This makes the LDA $1864 and CMP#$1E pointless, so I'd NOP them too, but it's not strictly necessary.