Knights of the Cardboard Castle

SpaceChem is a game that I’ve been wanting to write about for a long, long time. The reason it has taken so long is that it is such a hard, hard game to complete. I still can’t beat the final level, even after looking at online guides! I spent months on this game on and off but I’d bet it might take years for some people to master all of the user-uploaded levels. This is a game with seriously long legs but it will also give you agonizingly painful headaches.

This is a puzzle game centered around fake chemical engineering. A typical level represents an assignment in which you need to produce a certain number of a specific molecule. Molecules are composed of atoms and you manipulate them using waldoes. The gameplay consists of building the rail network over which these waldoes run, effectively designing a production system that will transform the input you’re given into the output that the level requires. This involves moving atoms around, bonding or unbonding atoms from each other, fusing atoms of one element to transform them to those of another element and much, much more.

Later levels make things harder by having you design multiple reactors working in conjunction to produce the required target molecules. You chain reactors together by feeding the output of one reactor to the input of another. You need to synchronize the actions of all waldoes correctly, juggle proportions of different atoms and do all this within a very limited space. The end of each stage typically involves a boss battle. You fight the boss by producing the right molecules in the right quantities at the right time to power the provided laser for example. These levels are much, much harder than the regular ones and often require throwing switches while your reactors are running to alter their state.

While the game pretends to be chemical engineering (and indeed the game provides you with the periodic table of elements which you need to use to figure out how to get from one element to another through fission / fusion reactions), it really amounts to a programming game. Tools like the flip-flops and sensors amount to loops and conditionals that together form a visual programming language. Since each reactor has two separate waldo tracks, one might even argue that this is multithreaded programming with each thread having different responsibilities and yet the overall work must still be synchronized. The analogy is so apt that the game is apparently used as a tool to teach fundamental programming concepts in some schools and one player claims to have implemented an interpreter for the esoteric brainfuck language in it.

What I personally love about this game is that the puzzles are open-ended. Most puzzle games have levels which have only one intended solution. Even Portal was guilty of this, with players finding alternate solutions only through exploits. By contrast once you become familiar with SpaceChem, it’s obvious that the objectives can be met in a bewildering number of ways. You can optimize solutions by time, achieving the objective in shortest possible time, or by using the least number of symbols, or instructions. The solutions posted on the leaderboards reveal some truly innovative and clever designs.

My only regret is that the game is too difficult for me. I can only honestly complete about 60% to 70% of the puzzles on my own. Many of the boss battles for example require a degree of coordination and imagination that is simply out of reach of my intellectual prowess. At the same time, when I do manage to honestly complete a puzzle, after spending many hours on it, the wave of satisfaction I feel is immensely rewarding. As one writer for Rock, Paper, Shotgun put it, a good puzzle game make you feel smart. But SpaceChem makes you feel like a god among men.

So yeah I give this game my highest possible recommendation. Anyone with the slightest interest in puzzles should check it out. Just be careful about how much of your time it can suck up.