A friend of mine is the dev on this game and it is a really interested co-op experience. Essentially, you and 4 friends can fly around in a ship that could be from Star Trek (but not due to the obvious license issue). A Captain, Tactical Officer, Helmsman, Engineer and Science Officer. But there are also smaller ships for 1,2 and 3 players as well. Oh, it is also free but there is a $2 option to have an upgraded account for more scenarios.
Its on kickstarter trying to get finds for the android version and some more add-ons to keep it interesting.
You can currently play it in your web browser, download it for Windows, Mac and certain iOS devices and coming soon is the Android version, and the cool part is, everyone plays together no matter what device you are on!
It currently does not have much of a player base but we are always looking for more people to play with.
So give it a try, and please consider funding the kick starter to help out!