Trading, combat and exploration in space!
Naev (Not Another Escape Velocity) is a single-player open-world sandbox space title. You begin with a basic ship and make your way through the cosmos completing jobs. Each system has a number of locations, most of which contain NPCs, missions, goods and ways to upgrade your ship.
The game boasts a multitude of options in terms of customizing your ship and ways to earn money. The overall map is always the same, but missions and NPCs vary greatly with each playthrough providing a fresh experience with each game. There's an overall story you can follow, but it's often lucrative to find side missions to complete while working on the main quests.
Naev is open source - there's a number of mods available and even alternate versions of the game with different content. It's a fun title and definitely worth a look if you like open-ended space games.