I don't get the time scale the game is based on.
Are all the durations you gave real time?
Surely harvesting hydrogen from gas giants and mining asteroids for ammonia shouldn't take months of real time?
Just wanted to clarify.
The problem with such a game would be that you're not providing the player with a specific and relatable goal. By relatable, I mean something like "destroy the other colonies and rule the galaxy" (that is of course an exaggeration). When you're developing a big budget game like that, you'l...