The latest version of the massively ambitious space thing Star Citizen (Star Citizen Alpha 2.1.2) can now be tried for free (for the next week) in what's being called a Free Fly Event. All you need to do is sign-up for an account, and then patiently wait for the 27.8 GB install to complete. Yeah it'll take a while, but once that's done you'll get access to a space ship to fly around with. And do a bunch of space things.

The Free Fly event gives everyone access to three unique parts of the Star Citizen experience:

Star Citizen Alpha 2.1.2 – Also known as Crusader or the “mini-PU,” this is the nucleus of the world we’re building! Featuring multiple space stations and environments, scripted missions, places to explore and more, Alpha 2.1.2 is your first look at a much larger universe!
Arena Commander – Arena Commander is a ‘game within a game’ that we’ve used to develop our flight mechanics and ship combat balance. Take on human opponents or an AI swarm in single seat fighter.
Social Module – Interact with other players while you explore our first landing zone, ArcCorp! The Social Module is intended as a starting point for our world building.

To find out more head to the official site.