Games like Sky Nations

StarMade is a free-to-play Sci-Fi Shooter game, currently in Alpha, that offers single-player, local multi-player, and online co-op/PvP gameplay. Players can support the developers by purchasing the game, which will grant access to future updates and exclusive features such as blueprint hosting and multiple skin uploads. Despite some optimization issues and bugs, the game offers plenty of humor and grinding for space exploration and battles.

Worlds Adrift is a sandbox MMO where players explore a vast, procedurally generated world in airships. Harvest resources, craft and customize your vessel, and engage with other players in a constantly evolving environment. Collaborate or compete as you navigate the challenges and mysteries of a fragmented, earth-like world.

"Starship EVO is a work-in-progress space sim that offers a creative building experience, allowing players to build and customize starships, space stations, and handheld weapons using a variety of tools and options. The game currently features engaging space battles and plans to add a survival mode in the future. A Server/Client framework is used for multiplayer, which requires port forwarding." less than 400 characters, more than 100 characters.

"Starbase" is a science fiction open-world game in early access that combines single-player, co-op, and massively multiplayer options with a focus on building, designing, and battling in space. Its destructible environment and hybrid voxel/vertex mechanics allow for detailed simulations and creativity, but expect some bugs and grinding. The game includes impressive graphics, exceptional music, and a full roadmap of upcoming features.

"Airmen" is a shooter game where players build and battle custom airships, either solo or with up to 2 players in co-op mode. The game features a variety of weapons and components to customize your airship, with the goal of exploring the Archipelago, gathering resources, and battling other players or AI forts. With a growing catalog of over 100 parts and the ability to co-op build with friends, "Airmen" offers a unique and engaging gameplay experience.

Avorion is a sandbox space simulation game that lets you build your own space ships and explore a procedurally generated universe. Mine resources, trade goods, and engage in space combat while navigating political alliances and factions. Experience a dynamic world that evolves based on your actions and interactions with other players.

"From The Depths" is a sandbox vehicle construction game where you can build and command battleships, planes, submarines, and more in intense battles. The game features a creative mode, a strategic campaign with eight factions, and a story mode. It also offers in-game planet, campaign, mission, and multiplayer map editors, as well as Steam workshop support for sharing your creations. Available on PC, Mac, and Linux.

Space Engineers is a sandbox game set in space, where players build, design, and maintain various types of space vessels and stations. It features both creative and survival modes, allowing players to either freely build and explore or survive in a hostile environment. The game also includes physics-based engineering and destruction, adding a layer of realism and challenge to space engineering.

"Reassembly" is a single-player Science Fiction Strategy game with good mechanics, fantastic visuals, and exceptional music, but a lackluster story and heavy grinding. Players craft and customize their own spaceship, battling a variety of alien races in a procedurally-generated universe. The game offers high replayability and unique atmosphere, but can be buggy. Growth and evolution of your ship adds a fresh twist to the strategy genre.

"Trailmakers is a physics-based vehicle construction sandbox game, where you can build and pilot cars, planes, and boats in a variety of environments. The game features a campaign mode, rally mode to learn building, and sandbox maps for creative building. Multiplayer mode supports up to eight players for cooperative or competitive gameplay. Use various weapons and blocks to build and customize your ultimate combat vehicle."