Great game, I liked it alot. Well executed tutorial and solid gameplay. I would have liked some more money, atleast after the tutorial. So I could really scale my server cluster.
The firewall could maybe benefit from a smaller defence and not protect so far out? I had a hard with the timing of moving it to protect the cluster. The big range of the firewall made me feel like I should stop all "red" requests. A smaller wall would maybe not imply that I could.
This is just nitpicking on a great game.
Good job!