SpaceChem is a puzzle and indie game by Zachtronics Industries, based on principles of automation and chemical bonding.

SpaceChem was the developer's first foray into a commercial title after a number of free Flash-based browser games that feature similar puzzle-based assembly problems.

Each reactor has up to two input and up to two output quadrants, and supports two waldos, red and blue, manipulated through command icons placed on the grid.

The commands direct the movement of the waldo, to pick up, rotate, and drop atoms and molecules, and to trigger reactor events such as chemical bond formation.

[1] As such, the player is challenged to create a visual program to accept the given inputs, disassemble and reassemble them as necessary, and deliver them to the target output areas to match the required product.

The player successfully completes each puzzle by constructing a program capable of repeatedly generating the required output, meeting a certain quota.

[1] Final boss levels, called out as defense levels, complete each planet; here, the player must efficiently create chemicals and deliver them in a timely manner, once the reactor systems have been started, to trigger defense systems to ward off attacking enemies before they destroy a control structure.

[2] Prior to SpaceChem, Zach Barth, the designer behind Zachtronics Industries, had created several Flash-based browser games with automation puzzles, including The Codex of Alchemical Engineering where the player had to place and program manipulator arms to construct atoms and molecules following the rules of alchemy.

[3] The team used the C# language built on the Mono framework for the game which would allow for easy porting to other platforms beyond Microsoft Windows.

The team designed puzzles based on general chemistry concepts without envisioning the specific solution that the player would take.

In some cases, Barth discovered that players made assumptions on limitations of the game from these tutorials such as the idea that the red and blue waldos must remain in the separate halves of the screen.

He also devised the means of sharing solutions through YouTube videos due to similar comments and discussions on the previous games.

[3] SpaceChem was released on January 1, 2011 via digital download from the Zachtronics website for Microsoft Windows, Mac OS X, and Linux computers.

[2][15] According to The Independent Games Developers Association, schools in the United Kingdom have started using SpaceChem to teach students fundamental programming concepts.

[16] The success of SpaceChem led to several companies contacting Zachtronics to develop educational titles; the company spent about two years working with Amplify to develop three "edutainment" games for their platform before they returned to work on more direct entertainment titles, but used the opportunity to improve on their in-game teaching mechanics.

[6] Gamasutra's Margaret Robertson praised SpaceChem's gameplay, contrasting it with other open-ended activities as it offers the opportunity for the player to be as creative as they want to be within the minimal ruleset required of each puzzle.

[3] Ryan Sumo, the freelance artist for the game, gained recognition in the industry and went on to help develop the art for Prison Architect.