The game concept for this is brilliant. Though it took me a bit to get all of it :P. But once I got the bit about building a new base, it came together well. Loved the planning out of where to set it, and to grow protection zones more.
I assume however the levels are procedurally made? As they differ each time after death. If this, then this accounts for some of them being (from what I can tell) unwinable. Less about strategy and more about luck.
If you continue this game (and please do), lay out the levels by hand. a bit more. It'll allow for more opportunity to improve and win over a level, and be able to learn and grow from previous failures on a level.
Really great game design though, really enjoyed playing!