The 2.0 version of Star Citizen is right now in limited Test Access. It will release fully in the next week or so.
If you don't know, 2.0 includes the first step of the whole universe. You can spawn in the Crusader system in a space station, take off, fly around the planet using your Quantum Drive (essentially hyper-space) visit other stations including a repair/refuel station and a derelict station where you can do EVA zero-g FPS combat. There is multicrew on big ships so you can get in a turret in the Constellation (kind of like the Mellenium Falcon) or the Retaliator (space B-29). There are AI pirates and many other things.
Pretty much this video shows and explains it all.
This second video (from gamescom) is a live demo by Chris Roberts and the team and it really shows what you can do. Also watch till the end, something pretty good happens.
Also, if you're interested in starting to play, you can buy starter packages for I believe $45 and you get a decent ship. Also use this referral code and you get 5,000 Credits ingame: STAR-6Z5W-J9PD You don't have to buy other ships (Sort of like DCS modules, but some more expensive!!!) to play, and if you're lucky, you might find someone who will let you fly or gun in their ship.