Thanks for the reply! Good question.
This won't surprise anybody, but sometimes people can get a little weird about their kinks. The current fade speed causes a couple of frustrations for me. I feel I have little time to admire any progress, and I find it impossible to get cheeks to "match". Once the desired glow is achieved on one cheek, switching to the other causes the first to fade back almost instantly it seems.
With some implements (like the hand) the marks fade so fast that to get any sense of progress I have to repeatedly smack one cheek with unnatural ferocity, which feels bad. It's not the girls' fault they recover so quickly.
I'm not against new toys, but that doesn't solve the problem for me. Tying the fade speed to implement implies each implement as an escalation of the last, and I'm not sure I want to see anything heavier than the paddle. I already avoid spanking the zombie girl because her marks look too much like bruises, which I discovered was a turn off for me.
So I suggest a Fade time option, with current fade speed being "fast" and a medium (2x) and slow (5x).
Or you could add an "aftercare" mode where marks fade extremely slowly unless massaged or rubbed (maybe add a "lotion" toy), and would introduce a new play cycle of spanking > rubbing > spanking etc...
Once again, great game, and thanks for asking!