Lately I came across a great game that has been around a while but deserves much more attention. The game I am talking about is called Starport: Galactic Empires. This game is 100% free (but people can buy so called "tokens" to support the creators of the game).
Players fly around in a spaceship in a persistant 2d universe, capturing colonies, trading, competing and fighting other players, and building colonies. The game offers many planet types ranging from nearly unhabitable volcanics to paradise worlds that have an overkill of each resource available.
You can modify your ship with modules that increase ship handling, cargo, and shield effectivity and many more. The game also offers many different ship types.
People can land on colonies where immediately a defensive system is activated. Lasers and the dangerous solar cannon will immediately open fire at your ship. As you try to hit the biodome on the colony itself with full energy, your heart can go pumping due to so much laser fire.
If you like a competitive, exciting, and last but not least free game, Starport is definitely the right game for you!
Hope to see you on one of the Starport servers soon!

http://www.starportgame.com/