I'll refrain from saying the mine-flagging thing other people mentioned, since this isn't going to be updated. But, as a general thing, it feels a bit odd that the only way for you to get the girls nude (as far as I've seen) is for a mine to blow up next to them, thus killing another girl in the process. I feel like getting to see the girls nude should be a reward for skillful play, rather than a sort of "silver lining" to making a mistake/failing a gamble.
Also, with regards to the mine-flagging, if you wanted to avoid making it take away from "the girls mark the mine presence", you could do something like... marking a "pathway" along tiles that the girls have stepped on. That would also help with another issue I found with this: The tedium of moving all the girls to the end once you'd found a safe path there. If you had this pathway mechanic, then once a pathway was adjacent to all end-points, you could have the girls automatically travel along it.