The Stack

[the Sequence] is probably my favorite acquisition of the Summer Sale. It’s a little bit Spacechem and a little bit The Incredible Machine, which kind of makes me realize that Spacechem was really a descendant of The Incredible Machine all along. All these games share a paradigm of setting up a mechanism and then letting it rip, trying it out to see if it does what you want it to do. As such, they’re all really about computer programming. But [the Sequence] doesn’t even pretend otherwise; it’s computer-themed, and its mechanisms, although spatially-arranged, are highly abstract.

Each level has the same objective: on a discrete grid, move a little round thing — officially a “binary data point”, but I can’t think of it as anything other than “the ball” — from a source tile that produces an endless stream of them to a goal. Getting four balls from start to goal without collisions is considered to be adequate proof that you’ve created a loop that can continue indefinitely. You accomplish this by placing objects on the grid that can move the ball around. For example, there’s a type of object that can push the ball one square away, another that can grab it from an adjacent tile and then rotate 90 degrees and drop it, another that’s a shuttle that moves one square in the direction it’s pointing every turn and can drag the ball with it, and so forth. These are represented by really well-designed abstract icons that clearly communicate what they do and where and in what direction. I won’t call them “intuitive”, because I don’t think you could guess their function purely from their appearance, but once you’ve seen them in action, they’re highly memorable.

The real trick, however, is that the objects don’t just affect the ball. They can also affect each other, effectively becoming nouns one moment, verbs the next. Like, maybe you need a pushing device in two different places, but have only one available in your inventory. That just means you need to construct a device to move that pusher around. There are even objects whose only purpose is to affect other objects, like the polarity reverser, which turns a pusher into a puller, or reverses the direction that a rotator rotates.

It’s all very much about lynchpins, flashes of insight about what the rules enable. A typical puzzle makes some aspect of the solution obvious, yet seems impossible: “The only thing I’ve got that’s capable of carrying the ball all that distance is a shuttle, but how do I get the shuttle back to the starting position without a polarity reverser?” And it’s kind of impressive how much it manages to force specific solutions through nothing more than the level geometry and the choice of tools. On the few occasions when I’ve been seriously stuck, it was because I was mistaking a puzzle’s intentions on a fairly high level.

The game’s title derives from the fact that the objects take turns. Getting the behavior you want often depends on adjusting the order in which the objects act. I’ve long felt that coarse placement grids are a good thing in contraption games, making the solutions more certain and less fiddly. Giving the player absolute control over the sequence of action effectively does the same thing for time.