Corrosion.

I’m a fan of midweight engine-building games, from Gizmos to Fantastic Factories to Wingspan to Everdell to Furnace; it doesn’t seem to matter what else is in the game, as long as there’s a straightforward engine-building mechanic and the game doesn’t take two hours or require a 20-page rulebook, I’m interested.

Corrosion appeared in the U.S. last winter, another import by Capstone Games (publishers of Ark Nova, one of the best games of 2022 so far), and seems to have slipped a bit under the radar, but I like its twist on engine-builders: Most of the machines you build, and even some of the parts you use to build them, will rust after a few turns and must be discarded. Only the most expensive machines, which require chrome gears that don’t rust, last for the remainder of the game. It reminded me in theme of the CPRG Baldur’s Gate, where weapons and other items you get in the early part of the game randomly fall apart because of impurities in the iron mined in that region, but here is seamlessly integrated into an engine-building game with some contract bonuses and very light deckbuilding elements as well.

Players in Corrosion are trying to build the most valuable factories, using three types of gears (small, medium, and chrome) and steam to do so, taking actions by playing engineer cards from their hands and placing them in the sector matching their number. You can recruit better engineers to improve your deck, and you can build “one-shot” machines that work one time and are discarded, “turning” machines that operate several turns until they rust, and two levels of permanent machines that require chrome to build but are also worth victory points at game-end. You can also take bonus certificates that give you game-end points for certain conditions, although doing so requires trashing an engineer card from your hand.

Each player’s board has four sectors on it and a wheel that you will turn one sector at a time; when the wheel’s fourth segment, marked X, passes a sector, the player discards all gears stored in that sector and all one-shot or turning machines built in that sector, retrieves any engineers played to that sector, and then activates all turning machines in other sectors and all permanent machines on their player boards.

The game ends when the supply of award certificates or of special victory point markers (which players can get in several ways) is about to run out, which means you don’t actually get that many of your own turns, so Corrosion also lets you follow other players’ actions if you want. When one player plays an engineer card, any other player can mimic that card’s action by playing an engineer from their own hands of the same color and a higher value (cards are 1-4 and 4+, which is wild and matches any color). It allows you to fine-tune some of your action choices during the game so you’re not just restricted to the engineers in your hand, while also giving more value to the recruiting action, as all of the engineers you’ll add to your hand are valued 2 and up.

Corrosion also comes with an excellent solo mode where you’re just trying to maximize your score before you run through the automa deck four times; all the automa player does is remove some engineers and machines from the display, which can include the chrome machines that also carry special victory points. It’s more a matter of cycling through the machines and engineers, occasionally tripping you up by removing something you wanted but also giving you more options, and testing your ability to build a productive engine. I haven’t cracked 50 points yet, which is a low bar to clear, but I do find the solo mode fun.

The art is great here, but I do think the darker industrial theme makes this look heavier than Gizmos or Fantastic Factories despite being of similar weight, possibly even lighter weight than FF is; those games, which I do like better than Corrosion for other reasons, have bright colors and almost goofy artwork that make them seem lighter. Gizmos is definitely easier to learn, but the engines you build aren’t any less complex, maybe even more complex than those here but without the rust mechanic. Games should take 60-75 minutes once everyone has the idea. I give it a thumbs up, even though I would probably always pull Gizmos off the shelf before this one.