Spaceforce: Rogue Universe is split into two different games. One is a story-driven campaign that has you traveling the galaxy in search of vengeance. The other is a free-form, open-world (or should I say, open-universe...) game where you create an in-game persona and travel the galaxy completing quests. Both are equally as entertaining, so there is no reason to feel like you are "missing out" if you choose one over the other. At the same time, the open-world part lasts a little longer and is a little more satisfying - so if you don't favor one or the other, go with the open one. Besides, the storytelling is pretty bad, so you really aren't missing a whole lot other than some cheesy dialogue and a better sense of direction. Still, it is nice to have the option of choosing which mode you would rather.
Either way, you begin with a basic fighter that you can upgrade or trade-in for other models. You can upgrade just about anything on the ship, giving it the "hot rod" feel of the Millennium Falcon. The only limiting factor is cash, which you earn by completing missions. Although the game boasts over 2000 missions, there are only 6 - 7 types of missions. Regardless of what missions entail, most of your time is spent locked in combat with other ships - so a good ship is key to any type of success. The upside is that there is always something to do; the downside is that some missions are outright tedious and pay very little - especially when you consider that the universe is a very, very expensive place.
When playing in the open-world portion of the game, you are given a choice of professions, each with advantages and disadvantages. In the long run, your choice of profession doesn't matter, though some are more helpful that others. A few of the profession bonuses relate to minor upgrades while others alter other aspects, mostly relating to the number of missiles you can carry or number of wingmen. Some abilities go unseen, so you may not notice they are working for you. Like nearly every other aspect of game, the lack of easy-to-access documentation kills player creation, leaving you with even more trial-and-error.