Think about modern-day NASA technology extrapolated 60 years into the future.
It is a sandbox game about engineering, construction, exploration and survival in space and on planets. Individual modules have real volume and storage capacity. Players build space ships, wheeled vehicles, space stations, planetary outposts of various sizes and uses (civil and military), pilot ships and travel through space to explore planets and gather resources to survive.
Space Engineers features a realistic, volumetric-based physics engine: everything in the game can be assembled, disassembled, damaged and destroyed.