Straight from GSB's website:
WELCOME TO GSB!
GSB is the ultimate space strategy game from UK indie developer Positech Games. It's a strategy / management / simulation game that does away with all the base building and delays and gets straight to the meat and potatoes of science-fiction games : The big space battles fought by huge spaceships with tons of laser beams and things going 'zap!', 'ka-boom!' and 'ka-pow!'. In GSB you put your ships together from modular components, arrange them into fleets, give your ships orders of engagement and then hope they emerge victorious from battle (or at least blow to bits in aesthetically pleasing ways).
Basically, you build ships up according to class: Fighters, then frigates than cruisers. Each ship hull and class has a set amount of hardpoints and equipment slots. Hardpoints are for weapons, and equipment slots are for your integral ship components.
The components range all the way from power generators, shields, armor all the way to weapons and engines. Your ship will need power, engines, shields and weapons to be an effective warcraft, but be careful of what you put on your ship: Certain components require more power or crew than others, and some are heavier than others, adding more weight slows your ship down.
The game originally had a set battle scenario mode, where you had to play out and win a scenario before the next one was unlocked. Now with all the new expansions and DLC and whatnot, GSB now has a campaign!
Adding to this, the game is extremely moddable: People have added ships from star wars, star trek, and tons of new scenarios!
And the game mechanics are top-notch as well. Before each battle, you organize your ships into fleets, give each a specific set of orders, and then the battle plays itself out like a movie. With literally hundreds of combinations of components and orders, this game has some intense replay value. Each scenario can be replayed on normal, hard or very hard.
Including top-notch graphics, quality sound and seven different races, GSB is a game that can and will keep you busy for hours.
And GSB is an Indie game! Grab the demo now!