@huvaakoodia I very much appreciate the in-depth commentary. Here are a few responses...
The game was poorly balanced and polished, yes. The idea took me a night of sleep to finally come, and I missed most of monday due to work, so I did it all in around 48 hours. I left polish and even basic interface (like a main menu) for later. This is not a defense, just maybe a statement of self-awareness, I suppose :P
My thought of "sacrifice" is that selling a grown tower means resources, but also means having to rely on weaker towers for a while, which can be devastating. Of course, as you've shown there are strategies that minimize the impact of the sacrifice. My personal one while play-testing was to sell two shrooms and replace them with 3 new ones until the base was surrounded and then start to work on the Shriekers.
Glad you had fun, and also glad to see a screenshot of a game I made posted by someone else. That's really satisfying. :)