Opus Magnum is a puzzle-based programming game developed by Zachtronics. It was released for Microsoft Windows, Linux and macOS in December 2017, following about two months of early access. In the game, the player must assemble a machine using various tools and program those tools to complete alchemy-related tasks. The player can produce any working solution to each problem, but is challenged through leaderboards to produce a machine that does the task in the shortest time, with the lowest cost of materials, and/or the smallest occupied area. It was based on The Codex of Alchemical Engineering, one of the earliest Flash games made by Zach Barth prior to establishing Zachtronics.