Okay, hear me out....
Invisibility.... A hand full of girls in town, and you're class mates with them (maybe another NERD storyline besides the Tentacle monster?) you create a serum that allows you to turn invisible for a certain period of time.
You only have enough time to do certain things (ie: steal their clothing, peep on them, spook them out, etc) Whether it be at their homes, gym locker room, or showers, etc. But you cant get caught in steam too much, because your silhouette will be visible, or you cant keep spooking them or touching them when there's more than one girl around or they'll find you out. Also, there'll be obsticles in your way too, like you have to avoid standing right in front of them when they're walking or they'll hit you, and/or you'll have to watch out accidentally walking into things (like in a kitchen, if you hit the counter too hard avoiding her, flour will fall on you or something to make you visible) BUT, if there is only one girl around, you can either take advantage of her (trap her) or you can convince her some crazy story (if she believes in the paranormal).
All this to add more of a challenging game feel. And because of the objectives being so light and timed (taking clothing, stalking, watching, effecting them with your actions) the re-playability will be really great.
?EDIT: Forgot to mention: I know it's a cliche story element, but you have to admit, the way the game is set up now a setting like this would use the current mechanic very well.
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