Escaped in 22 days. just buy the machine guns till you have enough to buy snipers. then upgrade your snipers and your pretty much set. IF ther are too many on the screen...just use your artillary (or better yet, time the birdies so they drop the bombs)
OK, I figured it out.... Heres how you beat it. Create a maze that has 2 different ends, like a letter Y. when the creatures get to one end BLOCK IT. They will turn, walk past the guns again, and make their way to the other end. SELL THE TOWER you made that forced them to turn around, and then block the other end. They will turn and walk all the way to the other side again. Just keep repeating this, and eventually they will be worn down and you'll beat the game.
After playing this a million times, I finally figured out how to beat it. Make a maze with 2 openings at the end, like a letter Y. when they get to one end, block it. They will turn around and walk part the guns again. Sell the blocker and prepare to block the other end when they get to it. repeat and keep upgrading. Line the path with missile launchers and upgrade them. Don't forget to take care of the flying ones though. Thats how you will die if you don't put the towers out that shoot only air. TRY IT! HAVE FUN!
Its like the tomatos in the airplane are dancing on the faces of the ducks which fly by carrying a newpaper autographed by the great santa clause-rodriguez!