Lovely game. I enjoyed it, especially the bonus story aspects giving depth to the characters and world. :3
When I was playing, though I know you mention "Shrink High", it reminds me more of a game called "The Diminutive Experience" (which may have also been inspired by SH, but I don't remember which came first), wherein you collect powerups and attempt to rescue other shrunken people as you dodge crushing stomps. Though I do like the idea of becoming friends with the bigs, rather than just trying not to die. xDDD
One thing you might consider adding in the future is more sinks for collected money. Because after you get all the upgrades there's not much more point in collecting it (at least that I can see). Perhaps you can unlock other things with it later like the variant stories, other missions or bonus art for the gallery. I'm sure you might have something in mind, but figured I'd mention it anyway.
Really great game so far and I look forward to future updates! Keep up the great work! ^^