Games like BossConstructor
Games like BossConstructor include Space Engineers, Kerbal Space Program, 鬼谷八荒 Tale of Immortal, Reassembly, and People Playground. We matched them by the tags players give BossConstructor on Steam (Indie, Action, RPG, Simulation, and Space): closest matches first, and among equally close ones the better-known games.

Space Engineers
Shared: Space · Building · Simulation

Kerbal Space Program
Shared: Simulation · Space · Indie

鬼谷八荒 Tale of Immortal
Shared: Simulation · RPG · Singleplayer

Reassembly
Shared: Space · Building · Action

People Playground
Shared: 2D · Simulation · Singleplayer

Cosmoteer: Starship Architect & Commander
Shared: Indie · Space · Building

Endless Sky
Shared: Space · Simulation · RPG

Oxygen Not Included
Shared: Building · Singleplayer · Simulation

Space Pirates and Zombies
Shared: Action · Indie · Space

Starcom: Nexus
Shared: RPG · Space · Action

Hardspace: Shipbreaker
Shared: Space · Simulation · Singleplayer

Empyrion - Galactic Survival
Shared: Simulation · Space · Building

Starpoint Gemini 2
Shared: RPG · Simulation · Space

Trailmakers
Shared: Action · Space · Singleplayer

Graveyard Keeper
Shared: RPG · Simulation · Indie

Space Pirates And Zombies 2
Shared: Action · Indie · Space

The Escapists
Shared: Indie · Simulation · Action

Between the Stars
Shared: Action · RPG · Indie

Space Engineers 2
Shared: Space · Building · Simulation

Rebel Galaxy
Shared: Space · RPG · Action

Terraria
Shared: 2D · Building · Indie

FTL: Faster Than Light
Shared: Indie · Space · Singleplayer

Stardew Valley
Shared: RPG · Simulation · Indie

Dust: An Elysian Tail
Shared: Action · Indie · RPG