The story is well explained in the TR site under media theres a cinematic trailer that is actually the intro of the game
Tabula Rasa there also some gameplay videos.
The quest system is very good lots of different quests, even quests with moral choices like this guy that gives you stolen medicines to sell someone and you can either do what he says or report to the commander that he has been stealing the medicines.
The item drops are ramdom and have ramdom stats with the color rank system aswell
but there are lots of different weapons (pistols, rifles, shotguns, machineguns, netguns, torqueshell rifles, blades, staffs, cannons, grenade launchers, flamethrowers, injector guns, polarity guns, leech guns and dunno if i missed any then there are different types of each weapon with different dmgs like fire, ice, laser, electric, sonic and EMP(electromagnetic pulse)) and armors, there are like 15 classes but with a tier system which means everyone starts being the same class, then at lvl 5 you can choose to be either soldier (damage dealer) or specialist (support class) then at lvl 15 soldiers can go comando or ranger and the specialist can go sapper or biotechnician and then at level 30 each lvl 15 class can select between 2 new classes and the max lvl is 50 and one of the good things its that you can clone your char before selecting your new class and that clone can select the other class or use it to respec your char, the clones have the same lvl and atributes but get the skills reseted so you can allocate them again.
There are also alien invasions in some bases and you have to help either defending it or assaulting it in the case the aliens are in the posesion of the control point, this is not really needed to advance in the game, just plain fun.
Theres also a crafting and dismantle system, you can extract the extra stats of a weapon and craft them into another or somethin like that i havent tried the crafting system yet.