this has been said before, but the game doesn't register when I hit a+s+d all at once, making the truth or dare song impossible. Other than that, it a pretty good game.
here's something interesting: not shooting gives you 2500 for accuracy, 100% accuracy gives you 1000*level. So don't shoot the first 2 levels, then just fire a couple of shots for the 100% bonus.
youtube has a couple of DTD vids of people who beat it. Basic strategy: use juggling + 1 maxed bash tower (possibly with 1 boost tower) to handle all the ground units, and spend everything else on swarms. Buy 1, 2, and 3 maxed snap towers for the last 3 non-boss flying waves respectively, and let the 2 air bosses on 99 through. It's still tough though.
for those who don't know, juggling is making a maze with 2 paths, then blocking one at the end with a cheap tower. when the enemies are most of the way down the other path, you sell the tower blocking the first path and put one down blocking the path they're on. The enemies move back and forth between the two paths, never reaching the exit if it's successful.
2 things help: 1, you can lose the end of the doll's limbs without dying, which makes you a smaller target. 2, only the bottom tip of the spikes kills you. you can run over them once the bottom is off the screen.
Patience is important. By the way, once you're strong enough to start doing the storyline missions and have 12+ people, you can easily increase their carrying capacity by filling your caravan with half food and half water (preferably several hundred of each), and then letting it sit on top of a town on the world map while you do something else. bad guys won't attack you until you move off, and strength goes up over time.
Well I feel like an idiot. The key is to buy boosts/skis/whistles as early as possible, because you can use each one you buy once per flight. They look like they're one use, but they're not. Knowing that makes it a lot easier.