Finished the entire two maps. Now there is nothing to do but go through the original maps again. Boring. No more challenge to the game.

It will eventually stop letting you do that maps unless you pay more. Says you have run out of defense. Done with this.

opens with some odd resolution that only uses half of my screen and does not work. I like the windows version of this, and it works perfectly. :(

I have played this game hundreds of times. It is just the right amount of challenging, with upgrades to help a revisit to some levels be more successful. The people who made this game designed it very well, there are a variety of options in each level, choices on when to use special powers, and choices on what power ups to buy. Some levels are too easy, and a few are barely possible, until you find the special way they intended you to play it. I am able to win without buying the extra items, but those extra items would make it more fun. Very well written app, no bugs, lots of fun!