A Guide to Patterns and Forms in Trainyard

The Multi-Loop

The simplest loops delay a car by four, six, eight, etc squares. You can add these loops in a variety of ways to create delays of any even number. But if you're short on space, you'll combine them into a Multi-Loop. There are almost an infinite number of ways to do this - the longest I've seen delayed a car by six million squares. Below, I'll show a series of increasingly complex Multi-Loops that delay a car more and more.

Track length: 9 steps

Track length: 9 + 4 = 13

Track length: 13 + 6 = 19

Track length: 19 + 4 = 23

Track length: 23 + 8 = 31

Track length: 31 + 4 = 35

As you can see, the possibilities for Multi-Loops are endless. When the puzzle's creator, Matt Rix, began allowing users to share solutions online, he quickly had to create a new sorting category for people who were trying to make the longest solutions, eventually adding a super-fast game mode so that players didn't have to leave the game running for days at a time.

That's the last of the major forms - I hope you found them useful or at least interesting. The last thing I wanted to write about here was how to go about optimizing your track to make it the coveted "Shortest Solution" or "Most Economical" on the Trainyard website.

Next: Optimizing Solutions

Comments

One really cool thing about multi-loops that I was surprised you didn’t mention is that you can treat a multi-loop as a binary number describing how many times a single train will loop before escaping!

This means by setting the initial position of the switches in a multi-loop (the bits, with the into-the-loop direction being 1 and the escape direction being 0) you can create a loop that goes an exact and predictable number of times! It’s a little weird because the least significant bit is the innermost loop so the bits are sort of backwards.

For example, the 23-length track with the double loop above will loop 3 times – the bits are “11″ because they’re pointing into the loop. The 19-length track only loops twice – the bits are “01″ as drawn but “10″ since the innermost loop is least significant, and “10″ in binary is, of course, 2!

I’ve used this before on Engineer mode puzzles when I had to delay a train for certain amounts of time – you can make a nice 3 or 4-bit multi-loop and increment the bits one at a time until you get the delay you need!

Mark -- March 6, 2012

Awesome – I’d thought of it in a mathematical way, but I really like the idea of Multi-Loops as binary.

I also didn’t include any mention of figure-8 Multi-Loops – do you know if the same binary pattern applies to those?

C. Liam Brown -- March 6, 2012

Have to admit I never much played with figure-8 loops so I’m not sure what properties they have.

Mark -- March 6, 2012

The binary-loop is useful for not only forcing a train to delay a specific journey, but also for executing an action a specific number of times (a splitter, for example).

Philip -- March 6, 2012

Like in this puzzle! :)

trainyard.ca/S4Ha

Mark -- March 6, 2012

Here is an obnoxiously long loop I made for Sapling:

trainyard.ca/2dbq7

Jon -- April 30, 2012

Nice. The longest one I know of is for Red Line: http://www.trainyard.ca/2cPcS

C. Liam Brown -- April 30, 2012