If you want a lower spec but stil gorgeous singleplayer and multiplayer (not a mmo type game though) game check out avorion. Somebody gifted it to me because they wanted me to try it so much and I am starting to see what they were on about with it.

No planets to land on and it ends up playing more like a 4x game late game I think but it is worth a look. Just download and use workshop ships if you feel overwhelmed with the building part.

store.steampowered.com/app/445220/Avorion/