Never thought that creating ships to blow alien ships up for no apparent reason or logic whatsoever could be so fun! :D
What you basically do is to design ships which, when deployed in battle, will help defeat the enemy fleet. Every victory you win will give you a credit like reward called Honour. You use this 'Honour' to buy new shiny gadgets or weapons that blaze nice looking beams of death onto your enemy.
There is no actual story line. The game is basically composed of about 10-15 setups (forgot the actual number while writing this :/) which all offer a different challenge along with a certain species to go against. This means that just because your ship designs and the fleet you deployed were successful against a certain race in such a scenario, doesn't mean that you will be as successful in another scenario with a different species. Not to mention certain scenarios having something called 'Spartial Anomalies' which can affect how well/poor your ships perform in terms of their weapons and defences.
There is also a multiplayer mode which tbh isnt what you actually think, it isnt a match-up with another player, see who wins and say "HAHA YOU SUCK!" kind of game. No, how it works, is that you mainly pick your map and make your own scenario, deploy your ships that you designed and upload them. The scenario is then uploaded to a vast list of scenarios for the community to try out. Some may even consider retaliating your challenge. However i would just recommend trying out created scenarios to try out since there is a vast list of uploads that there is only a small chance of someone actually trying it out your own.
With every game however, it has its drawbacks...
Not counting the DLC, you may find it fustrating when you find yourself losing and on the recieving end of super intense beams of destruction blowing your stuff to smithereens, again and again. After the battle you are shown stats which are near impossible to understand, so you may end up in a repeating scenario of losing, losing, losing, then after more losing looking at the stats in attempt to study what is wrong, make new ship designs, still lose, go back to the drawing board, still lose and then wondering why the hell you cannot win when you study the stats for almost an hour. Also without the DLC you may end up finding yourself bored with just 4 races at your disposal, one of which you cannot fight on the single player mission scenarios.
As a result you may find yourself thinking that you wasted your money on a game you cannot understand and find out how little content you had. I would advice buying this game when there is some sort of sale or deal going on with this game. Buy with the DLC expansions too to give the game a little more spice to your experience with the game. That and a lot of patience with the losing and looking up for tips on certain situations and you may end up actually coming back to this every now and then.
Despite these flaws, GSB is quite a fun little game to kill an hour or so...just don't expect to fall in love with all the info you are bombarded with at the end of the battle. Again i would advise getting the DLC's as they include an extra 6 races to try and mess around with and a Galactic Campaign, though i would avoid not getting to engrossed in that too much due to the Galactic Campaign having some flaws, but the rest should keep you occupied with this game for even longer.
It may have moments where you say ♥♥♥♥ THIS GAME, ♥♥♥♥ ITS MECHANICS, I WANT MY MONEY BACK!, but stick to it and hopefully in the end you will be glad you bought this game along with the DLC's.
Despite its flaws which may end up annoying you with stats and at times fleets that make you think this is all impossible to understand, but overtime it can be really fun to play, maybe you could one day decide to play out of rage and take out your anger on a bunch of aliens who have no reason to be blown up whatsoever, except for your entertainment of zero-g fireworks!