Quoted from bkerins:
The first mystery award in every game is Advance to Monster. After that, it's randomized, but it is possible for later mystery awards to also be Advance to Monster, or for other awards (Advance 2 Rooms) to award progress that gives the monster.
I personally think it would be neat if we could change it to be truly random in the settings (or pseudo random, so it looks more random).
Alternatively, if we had a way to specify Easy, Normal, Hard, Insane difficulty we could change it.
Easy - Always to go Advance Monster, modes are counted regardless of completion, modes do not time out, etc..al
Normal - As current
Hard - Random mystery award + other stuff?
Insane - Never give Advance to Monster, modes end after song ends, only count if you complete it, etc...
I've always liked how video games give you easy, normal, hard modes. Pinballs have things like Tournament Mode, but would be awesome if we could make the game much harder if we wanted to. Some folks are masochists.