Really fun game! I played until I pretty much maxed out (when the cost scaling got insane). It could use some balance tweaks. The bombs never became useful because the stacks wouldn't get high enough. The punchers were too weak. Or maybe an additional building on top of the punchers for launching the seeds. I wanted to get higher stacks to make use of the bombers but the collectors were too fast compared to the punchers. I also think it would've been nice if the cost scaling didn't soft-lock you.
I think it would add to the satisfaction factor if the whole game fit in one screen, so you could see it all happening at once. Maybe by making the buildings build upwards into multiple stories, to take up less horizontal space? Just an idea.
These are all nitpicks because it was a fun experience that held my attention. Nice sound and art too.