First Impression: Opus Magnum is a puzzle game based around optimizing alchemy machines. You design and provide instructions for an alchemy machine and can try to optimize around cost, speed, or size. You design the machines on a hex grid and have a variety of different components you can place, including rotators, pistons, and various glyphs that combine or transform individual elements. You also choose where the component inputs and outputs are placed. Then, you provide step by step instructions for each component, telling them how to rotate or extend. The game also has some small bits of dialogue between each level, adding some context and tying each level together.
Going Further: As you play through the campaign of Opus Magnum, you follow a recently graduated alchemist who has just joined a struggling house. You are introduced to several different characters and each level you create increasingly complex compounds as a task for someone. The level progression is smooth; tasks become more challenging and complex but never get overwhelmingly frustrating. New mechanics are gradually introduced as you progress and have helpful popups to explain them. This, coupled with the vastly different form of each compound you create, keeps each level feeling unique. Even once you finish all five main campaign chapters, there is still plenty to do. There are over a dozen challenge levels of much more complex compounds for you to create (though the button to bring these is somewhat hidden in the bottom right-hand corner). Furthermore, both the campaign and the challenge levels can be replayed to try to design a new machine that improves in either cost, speed, or size. Each level has a set of graphs, displaying where you stand relative to other people who have played the level as well as showing you how well any of your Steam friends did on the level. There is also a minigame, substantially different from the main that you can play starting partway through the first chapter. It is completely optional, but (while confusing at first) is also quite fun.