OK it’s official, I have an addiction to Indie games at the moment. My Steam library is bursting with these budget curiosities that I have accrued over years of Steam Sales and Humble Bundles, and the guilt of leaving them behind to play their bigger budget cousins has become too much to bear. I simply must play them all! This time it is the turn of SpaceChem, a puzzle title with an unusual chemistry theme and, well, set in space probably.
SpaceChem tasks you with programming chemical reactors that can take some input molecules or atoms, chew them up a bit, then spit out something useful at the other end. These reactors each consist of a 10×8 square grid upon which you can trace the paths of two robots that will perform the preordained instructions that you give them. These two robots (called waldos, rather charmingly) are unable to interact with eachother directly, so you must use clever timing and logic in order to get the reactor to run smoothly. They are, however, capable of receiving a number of different instructions such as summoning an input into the reactor, picking up an atom and carrying it around for a bit, dropping the atom again somewhere else and spitting it out the other end of the reactor. This basic loop can be “fluffed up” at various points to produce some very complicated machines – you’ll be constantly surprising yourself at your ability to construct what seem like very intricate algorithms but what are actually straightforwardly construct-able from the constituent pieces given to you.
There’s something eerily satisfying about watching your reactors whir around and do your bidding ad infinitum. The dumb computational nature of the puzzle solutions would, however, become a bit tedious if it you were confined to one reactor per level for the whole game, but after the first couple of intro puzzles the solutions will require you to chain reactors together in longer and longer sequences in order to overcome the limitations of each reactor individually. The game has a well implemented difficulty curve with each set of levels introducing extra commands and mechanics that all feel very natural, while making the experience more challenging and rewarding.
The game really steps up a gear when it throws variable inputs at you – my god does it really become something special at that point. Suddenly that input command could summon forth an oxygen atom half the time, and a nitrogen atom the other half, for example, or even one of three choices! This is where the real meat of the game lies for me, as now you have to create “sorting” reactors that can distinguish the different chemicals being flung around and develop logic to deal with more than one scenario. This combination of different styles of reactor adds so much flesh to the puzzles, and further ups the satisfaction when it all clicks together.
There’s no traditional scoring system in this game, you are merely given a run-down of your solution once the mission is complete: commands used, time taken etc. This simple mechanic drives you to create even more efficient machines, and ones in which the robot paths loop across themselves in such ways that you can reuse instructions that have been laid on their paths at no extra cost. This might seem like a cheap way to build replayability into a game, but it’s exactly what the game needs – it’s so good at presenting the puzzles to you and building your skills in solving them, that it can be relatively easy to actually complete the puzzle most of the time. It’s not until the end of the level when you are presented with your score as compared with other people who have the played the game previously that you start to challenge yourself to come up with a more economical solution each time.
The one thing the game falls a bit flat on are the defense assignments. These are just like normal levels but you must make it so your system can spit out molecules at certain times or rates in order to complete some kind of environmental challenge. The mission pictured has you channelling a chemical into the top input of a machine half the time, then watching for the moment to flick the switch to pump something into the other input. The problem with these missions is that they are pretty poorly explained (unlike the rest of the game), and they don’t feel like a nice implementation of the game mechanics. I felt much more at home simply watching my creations chug along at a nice pedestrian rate until I had supplied all the molecules, not fiddling around switching between inside and outside views to keep checking the progress or position of the mission target. I think some people will find these missions more exciting and a nice change of pace for the game, but I would have preferred they were left out.
For me, this is one of the most beautifully constructed puzzle games in existence. The learning curve is perfectly pitched, the introduction of game mechanics has you always excited to see what the next batch of levels will bring, and there is tonnes of replayability in trying to get your solutions as efficient as possible. I would highly recommend this title to any fans of logic puzzles and abstract games.