After last release of the Earth Defence I received some comments that it is really easy to cheat :P Because there was no limitation of the number of rockets you could just tap the screen quickly around to pass the levels. This is why in v0.91 I added limited number of rockets per every level. Now, to pass the levels, you have to be accurate and you have to calculate your rockets :) Remained rockets are accumulated and passed to the next levels. You will definitely need them in the harder levels.
Good luck and thanks once again for the suggestions. I really appreciate them.