Starport bills itself as a free "winnable massively-multiplayer game" that takes place in space on a 2D plane. That might immediately bring Subspace to mind, and the presentation does actually appear very similar on the surface. There's a lot more to Starport than simple combat however. Ships can be upgraded and your individual pilot-player-character is customized from the beginning. There is a big universe to explore and developing colonies is important to improving your position in the games. It ends up being your job to beef up colony defense and protect your resources against raiding players. The game is almost more of a strategic simulator than a space combat sim. Game sessions last just two weeks, and a winner is announced at the end of each game.
Sound pretty neat for a free game? The developers make their money from in-game purchases. Various upgrades cost real life cash to obtain, and of course, everything is reset every two weeks. It's an interesting substitution for a monthly subscription fee. Since barriers to entry seem relatively low, this one might be a neat game for a group of Wing Commander fans to try out together. More pictures and descriptions of the game can be found here.