It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

First off, I really like this game. :-)
I especially like that you can go back and play any part of the story at any time and just play with it, even after winning campaign!

Second the fortress building, in planetary campaign mode, needs to be tier 2.
It's main function is to allow capture points to hold off the little guys that slip past the player group and that is very important mid game to late game.

Right now it's a huge pain in the ass mid-game because of so many places the basic enemies can come from, which makes it very annoying and takes away from the attacking FAR more then is reasonable.

If you need to swap something in tier 2, use the new death cloud.. it basically locks down an entire area for the duration.
That's MASSIVELY powerful compared to the fortress upgrade.