Vega Strike is an free and Open Source 3D Action-Space-Sim (works on Windows, Linux and Mac OSX) that lets you trade, fight, and explore in a vast universe .
Vega Strike aims to insert players into a large, dynamic universe with diverse factions of varying disposition to the player and to each other, and an economy model where trade, combat and exploration are all profitable. Financial gains allow the player to buy upgrades and/or better vehicles, thus enabling him/her to advance into more dangerous and profitable missions. The player can have varying levels of relations with factions. Negative relations can form if the player kills some of a given faction’s ships. Positive relations can be formed if the player destroys ships that are part of an enemy to a given faction. Players can either buy and sell cargo, or accept missions from the Mission Computer, as well as talking to people in the local bar at the space station/planet. In the tradition of some precursor games, individuals of significant plot importance are often found in bars.