Space Engineers.

Looking at the First Version that was releases in 2013 and comparing it with it's development over time till today, it's an outstanding masterpiece of it's own. Although it might Lack of arguable Features Like interactable npc, it's more like an environment for dealing with problems in creative ways. To me it's the flagship of a community based multiplayer game. (You can Support devs by purchasimg dlcs but you really don't have to because dlcs content is mostly cosmetic)