UPDATE: Now you only have 3 SCVs, and neither they nor any you make can build advanced structures, so that takes care of the tech tree problem. The only advanced structures you get are the ones in the base you rescue. (The factory and the ghost academy.) As for Jimmy, he now has 200 hp along with 2 armor, so he's less likely to get smoked.
Hi fellas. This is a remake of Backwater Station where you have to destroy the infested command center. Sadly, there is no such building in the editor, so the best I can do is a normal command center with a bunch of spike doodads in the middle of it. Anyway, this is much like the original, featuring an extra base that is neutral but will convert to you when you enter it with Raynor, who is a hero Hellion. He's not any more powerful than a normal one though, so keep him in the rear if you can. I used a desert map called "curse's fall" or something like that to make this mission. The enemies aren't too tough, but you don't get off so easy either. It's balanced, just like in the original. Enjoy!