One problem I see, you didn't bring in any of the core philosophy that was the entire point of flatland, i.e. how a three dimensional object would look to a simple 2D geometric world and what the implications would mean for the society at large. I was hoping for more than just a stabbity quest, although it wasn't a made game, just not nearly as much as I had hoped.
My biggest problem seems to be that there isn't an obvious pause button that lets me slow things down to plan my next move. Days shouldn't tick by in seconds. If I get distracted by something (even my cat jumping on the keyboard) a whole month can go by and I can't even train, conquer or earn cash. That sucks.
Seriously, you need to either add a low quality button or clean up your code. This is the ONLY game on Kong that I have found that slows down my comp...
Needs an auto save or an obvious save button in between levels. My game crashed (seemed to be flash based as youtube did as well) and I had to completely restart after getting to level 5 or something.
The moving the plane backward bug is retarded. Also, if you want to finish as quick as possible (in game days), just move the plane backwards, if you do it right, you can get the plane to fly forever, racking up huge cash. Of course, such an easy exploit of a bug that should have been fixed the day after release is one of the many reasons I am rating 1/5 until it is fixed. Heck, the bug even triggers in my game when I am not trying to move the plane backwards...
Seriously, a mute button isn't exactly the hardest thing to code and frankly your game is a bit loud compared to others... You started at 3/5 straight out. It only goes down from there.