Single-player games like Main Assembly
Below are 11 single-player Steam games similar to Main Assembly, ranked by player overlap. Every pick carries Steam's Single-player category, so multiplayer-only titles or always-online games don't sneak in. imho.run pulls the category data from Steam directly — Single-player here matches what the store labels.
Want the full alternatives list (paid + free + Steam Deck + cheaper picks)? See the parent games like Main Assembly page.
Ranked picks
- 1
Plasma
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
Plasma is a pure engineering sandbox. Use advanced visual programming and robotics tools to create anything you can imagine.
- 2
Archean
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
Gather resources, craft components, build vehicles, and code their logic in a physics-driven engineering sandbox and full scale space sim.
- 3
Stormworks: Build and Rescue
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
Join a world where you design, create and pilot your own air sea rescue service. Release your inner hero as you battle fierce storms out at sea to rescue those in need.
- 4
Nimbatus - The Space Drone Constructor
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
Command the Nimbatus and craft drones out of hundreds of different parts. Survive unknown threats in a fully destructible, procedural universe, compete against other players in different arenas or enjoy complete creative freedom in the sandbox.
- 5
World of Contraptions
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
World of Contraptions is a physics-based building game in which you build the most varied contraptions to solve the most diverse types of puzzles. Win dozens of levels with different types of obstacles. Design the best contraption for each challenge using a giant collection of blocks.
- 6
Besiege
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
Besiege is a physics building game about constructing medieval machines to annihilate armies, obliterate castles and overcome challenging obstacles. Conquer the campaign or skirmish with friends in Multiplayer!
- 7
TerraTech
Single-player alternative to Main Assembly — playable solo, no multiplayer required.
TerraTech is an open-world, sandbox adventure game, where you design and build your own creations through a mix of crafting, combat and discovery. Design vehicles from a huge library of blocks. Scavenge, craft and buy new parts to survive and become the ultimate planetary prospector.
- 8
KitHack Model Club
Single-player alternative to Main Assembly — playable solo, no multiplayer required.
Developed by the creator of the original Kerbal Space Program, KitHack Model Club is a physics-based model building sandbox that offers limitless freedom for you and your friends. Design, build, battle, fly (and crash!) your very own RC vehicles, or experiment with over 2,400 ready-made vehicles!
- 9
Scrap Mechanic
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
Enter the creative paradise of Scrap Mechanic! Build fantastic machines, go on adventures with your friends and defend against waves of evil Farmbots in this imaginative multiplayer survival sandbox. With Scrap Mechanic’s powerful creation tools you can engineer your own adventures!
- 10
Trailmakers
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
Build the ultimate vehicle and explore a vast open world filled with challenges and adventure. Play solo or team up with friends in multiplayer to conquer the toughest obstacles. With a thrilling campaign mode and endless creative possibilities, Trailmakers is the ultimate sandbox for adventurers.
- 11
SimplePlanes 2
Single-player alternative to Main Assembly — playable solo, no multiplayer required. Shares Simulation with Main Assembly.
SimplePlanes is back! Build planes, cars, or anything else using powerful procedural parts! Explore detailed environments with friends in multiplayer, cause chaos, or download 1,000,000 community crafts for free.