Arena Commander is going to be a full game and the first part of the Star Citizen universe. it contains 4 parts: free flight (single player), Battle Royal (free for all multiplayer), Vanduul Swarm (single player vs AI), and Capture the Core (multiplayer FPS- team king of the hill). it will be available for a base price of $35. that's $30 for a basic ship and $5 for Arena Commander accesses.
the next part of Star Citizen will be Squadron 42. it too will be a full game with a storyline that will cover the lore of the universe as well as act as a tutorial preparing the player for introduction to the final part of the game, the persistent universe which is now up to 125 star systems with the UEE and 4 alien races.the persistent universe is scheduled for early 2015.
so far Arena Commander is on track for release by the end of May.
a player made trailer