Space Engineers is a voxel-based sandbox game, developed and published by Czech independent developer Keen Software House. In 2013, the initial developmental release of the game joined the Steam early access program. During the following years of active development, Space Engineers sold over one million units. As of 2024, the game has sold over 5 million copies. In May 2015, for approximately a year and a half, the game's source code was officially available and maintained by KSH to assist the modding community. On December 15, 2016, the game entered Beta and was later officially released on February 28, 2019.

Space Engineers is 3D singleplayer and multiplayer sandbox game, which doesn't have a specific end goal. Instead, the players (Space Engineers - Astronauts) are encouraged to create their own goals, which they have to achieve, by utilising engineering, in space and/or planetery environments (including asteroids and moons). More specifically, the players use a combination strategically placed "blocks", game mechanics and system interactions, to gradually build up to their goal. For example, creating a space ship that can go to space. Although, for players that want a more specific end goal, the game includes some built-in npc interactions, but it also provides a collection of pre-included story driven scenarios to choose from, while also providing the ability to use custom instances created by other users, both based around the core game. Expanding on that, the game furthermore offers the ability of using custom player made scripts and/or mods, to enchance or build on the already existing in-game vanilla content, which are also sometimes used in custom made scenarios. Finally, it is worth mentioning that the players can also share their builds amongst them, through the use of blueprints, has two modes, survival and creative, and that the game has the unique characteristic, compared to other games in its genre, to be able to allow players to fully interact with their creations, without any major limitations.

Players begin by selecting or joining a world with customizable settings. These settings determine features such as the number and arrangement of asteroids, the inclusion of planets, and the starting equipment provided. During world creation, advanced options allow players to modify gameplay dynamics, such as tool and machine efficiency, inventory capacity, and whether procedural generation is enabled—effectively creating an infinite universe.

Once in-game, the player controls a customizable astronaut, known as a "Space Engineer," equipped with tools including a drill, welder, and grinder (if enabled). Gameplay revolves around the construction and management of voxel-based structures, starting with the placement of foundational blocks. Players can create grids by placing blocks freely in open space, which form the basis of ships, stations, or other constructs.

Each block has specific properties, serving structural, functional, aesthetic, or interactive roles. For example, armor blocks are the primary building material and can deform or be destroyed through collisions or weapon fire. Functional blocks, such as assemblers and refineries, require power, which can be generated by solar panels or reactors.

Players can create three types of structures:

Grids are classified as small or large based on initial block size. A block intersecting terrain forms a station, and a stationary large grid ship can be converted to a station via the ship interface. Functional connections often use conveyors for resource and power transfer. Grids can connect through methods like connector blocks or landing gear.

All placeable objects can be colored before they are placed using a slider-based graphical user interface (GUI). Players can adjust the hue, saturation, and value of the color, allowing for a wide spectrum of options. There are 14 slots available to save new colors for future use within the same world.