Alternative #1: Starbound first of all is a 2d game. It sort of has the same space travel but more linear, it has hundreds of planets to explore I am pretty sure they are just randomly generated and has a lot more content. [spoiler]There is a game similar to Starbound but without the space travel and only has 1 world, called Terraria, it's a lot better than starbound.[/spoiler] Alternative #2: Space engineers. Space engineers is still in development but is in a pretty good spot currently to play. Its a survival game. This game is complicated and you have set world's and different scenarios. The "worlds" though can have multiple planets in them though and their moons. If you manage to figure out how to play it you can build your own ships and so on. It really tries to be realistic as possible when it comes to space survival. Alternative #3: Star Citizen. This game is still in development as well. It's basically what no mans sky would have been but without the planets. You are in a world with other players and collect resources fight for them get better stuff so on. Other than that I don't know much about it. I know it takes quite a computer to run though. Alternative #4: Elite dangerous. I don't know anything about this game. Only seen pictures.