https://naev.org
This is a project that's been headed by our project head bobbens for over a decade now, so there's a good chance you've heard of it. But here's a summary (copied from the readme):
Naev is a 2D space trading and combat game, taking inspiration from the Escape Velocity series, among others.
You pilot a space ship from a top-down perspective, and are more or less free to do what you want. As the genre name implies, you’re able to trade and engage in combat at will. Beyond that, there’s an ever-growing number of storyline missions, equipment, and ships; Even the galaxy itself grows larger with each release. For the literarily-inclined, there are large amounts of lore accompanying everything from planets to equipment.
We've had an influx of new contributors to Naev lately, which has been real nice to see. But if you like this game, we could always use more, so feel free to jump in!
We in particular could always use new mission authors and artists. Discussion of Naev's development usually happens on Discord these days, although the Naev GitHub page also has early access to the Discussions feature enabled (replacement for the old forum which was lost some time ago) for long-form discussions. So if you're interested in joining us, don't be afraid to get in touch with us from either of those avenues, or to browse the issue list. (Just a note, this isn't my project; I'm just one of many project members. bobbens is the project head.)