By the way, damsel, they don't just try to beat the level in a few minutes, they beat it as fast as possible using efficiency methods and even energy management. That is what makes it the challenge. In the end people try to challenge themselves in various ways and they're all nice, for example trying to get the best survival time, or letting the creeper pile up for >40 minutes before firing a single shot.
10/19 is awesome on agressive mortar-only! :D I barely managed to finish my first mortar in time to protect the supply line, and the second+third barely enough to attack + defend the supply line more when the second part got endangered!
Without reactors I managed to conquer the sea but the final push was too slow, should have built up more to the back first. And the right island also works, you can barely get to the center in time. :) Then you need to start conquering the sea with a bit of built-up supply from the top. I'm going to try again later, see if I can manage without reactors.
After lots of clumsiness I am finally holding the line in the west, destroying everything coming over the ridge, while making a slow push north as well. :) The third connector will be complicated but the general map is won.