Decent story and decent, if repetitive, music, but that's all I liked about it.
You need to work on your drawing skills, as all the girls had the same marshmallow face.
Passing the tinies off as "retro" is no excuse for bad pixel art; more importantly they don't even match the style of the rest of the game environment.
More importantly the gameplay has no merit. I ended up skipping through the rest of the game after i reached level three. There is no way to predict the giantess's movement much less avoid her foot besides sheer luck. As has been mentioned tacks are pointless as they cannot be put down and don't even save the personnel when they get stepped on.
Overall, I like the concept but the art and gameplay will have to be completely reworked for this game to be fun.