Well, I lost all my save data (which wasn't much) just by hitting the X to exit the browser. So every time I do that, I will have to start over!? Suppose it is on idle while someone else hits the exits the browser. Now, I just have to be careful.
Finally beat the game! It may be hard but that's what I like about it. It really makes you think so you have to try different strategies. Of your stuck on a level here's what I do - use one plane as a lure and all the others use to tail that one.