A few things made it hard to review this game. The first of those, and the most influential of them, is that it is essentially a demo. Not a complete product, and thus I can't measure it against its current form, but the possibilities that it shows. And it shows some promise. It is always good to see people starting into game design, and it's my policy to encourage them.
As such, the initial idea, though only very roughly formed, is interesting. The platformer genre is constantly overused to introduce characters people can't find a way to make any other kind of game about, but this one seems, if I'm reading it correctly, to fit the platforming rather nicely. The negative of this point is as I've already mentioned. Your idea isn't very clear, and your introduction is crude and hard to follow. A little more time, a little more characterization, and a clearly written script would vastly improve the flow and enjoyment of the game.
Your controls are fairly well implemented, and for a new designer they're pretty good. They are fairly floaty, however, and could use some tightening. Most surfaces seem to be slippery and difficult to land on even in the best of circumstances.
The graphics are consistent and at least vaguely themed, which is vastly more than can be said for many other first games uploaded to NG. That being said, I don't think it's a surprise when I say that they are limited and very rough. Demos being demos, I'm not going to push that point.
I love the size transformation mechanic. It's well implemented, well thought out, and honestly one of those odd things that I just plain enjoy. My only issue is that there's no explaination at the beginning of said size changes effects, so the player is left to find out for themselves that being large means you can't jump as high, and often get stuck in pits. Consider adding some tutorial text to level two.
All in all, it's a nice little game that has a lot of potential. I look forward to seeing the completed product, hopefully with little tweaks to problem areas.