If you're the sort who likes to have an elaborate rule book or instructional manual to consult when you're playing a game, Trainyard will be a bit frustrating for you; the game lacks that sort of documentation. Instead, newbies are referred to a short YouTube video on the game's official Web site, Trainyard.ca. But even the video merely hints at how the game is played. "It's kind of hard to explain in words," developer Rix writes [source: Rix].
Nevertheless, we'll give it a try. Trainyard essentially is a single-player game. While it's possible for multiple people to pass the iPhone or iPad around and play, each of them is really playing against the particular puzzles that he or she chooses, rather than against each other. There's no scoreboard that tallies points, and as one of the tutorials included with the game explains, there's no clock or time limit to use in judging somebody the winner.
Beyond that, there are many different ways to solve the game's more complicated puzzles. Like scientific hypothesizing, the way to distinguish yourself at Trainyard is by coming up with the most elegant -- i.e., the simplest and clearest -- solution to a puzzle. In science, that standard is sometimes known as the principle of parsimony, which dictates that it's pointless to do with more what's possible to do with less [source: Philosophy of Science, Resources for Beginners].
When you tap on the Trainyard icon to launch the game, you click the start button and then pick one of the game's 100 puzzles to play. The playing field is a grid with various colored markers that represent trains' starting stations and goal stations. As one of the game's animated tutorials explains, the "outlet station" has a plus symbol on it, and the "goal station" has a circle.
A Trainyard player's job is to get each train from its outlet station to its goal station by drawing paths on the puzzle pattern with his or her finger [source: Trainyard Instructional Video]. Each train starts out a certain color, and each goal station is a certain color. A train of a certain color must travel to a station of that same color.
Some puzzles involve more than one train. In that case, a player may need to merge trains together to create one train that is the correct color to match up with a particular station. For example, for a yellow and a blue train to make it to a green station, they must be merged -- since yellow and blue make green [source: Rix]. As you progress and play harder and harder games, you'll be introduced to other tricks and obstacles. For example, you'll find stations that will split trains back into two colors and other stations that repaint trains. You may need to route your train through one or more of these stations on the way to its goal.
As you can see, the game can quickly become complicated. We'll discuss how it stretches your brain on the next page.