Puzzle Trail

A Puzzle Trail is a particular type of hunt structure where teams only see one puzzle at a time, needing to solve each puzzle in order to view the next puzzle in line. It can be seen as a special case of Adjacency Unlocks where the "map" of the hunt is a single line.

Etymology
The Puzzle Trail is named because, much like a hiking trail, there's usually a single path of puzzles that teams are required to do in a prescribed sequence.

Pre-hunt History
The earliest forms of the Puzzle Trail can be seen in the, where a clue is given for a location of where a treasure could be. Often the setting used for this is a pirate, though this is largely a myth propagated by several novels written in the 19th century. Various high-profile puzzle contests have involved finding treasure buried in a particular location, such as the treasure hunt, which inspired a genre today known as an armchair treasure hunt. Perhaps the most famous of these is Pablo's Armchair Treasure Hunt. Separately, treasure hunts have also inspired The Game, which can be seen as a progenitor to most modern puzzle hunts that are of this format today.

In the early 2000's, with the increasing popularity of the Internet, many online Puzzle Trails were made (including, perhaps the most famous of the genre). This was because these sites were relatively easy to host as a collection of webpages where the goal is to determine the URL of the next webpage. However, puzzles in these websites often tend to be less structured, leading to moniker of "Riddle Trail" to be sometimes used.

Hunt History
Many of today's live walking hunts can trace their history to The Game. Due to the size of The Game, fewer organizers were able to host full-scale versions, and instead many smaller-scale versions were run. The first ones to show up were Bay Area Night Game (BANG) and Seattle and Nearby Adventures in Puzzling (SNAP). Cocasts (where an event would run in both locations, possibly at different times) would later inspire Different Area, Same Hunt (DASH). Other cities would also have their own walking hunts as well, such as the Boston Area Puzzle Hunt League (BAPHL) and D.C. Puzzle Hunters (DCPH®).

Additionally, later games used the ClueKeeper app, which greatly facilitates Puzzle Trail hunts due to the app's ability to give teams the next location upon entering the answer to a given puzzle.

There are a few online hunts that exhibit the Puzzle Trail behavior. Edric's Treasure Hunt and his Manhunt loosely follow this structure, requiring teams to change URL's to get to the next puzzle. Octothorpean is an introductory hunt that is mostly a linear Puzzle Trail, though there are times where the path branches.

Hunt Application
There are certain pros and cons to using a Puzzle Trail system, with many pros being particularly useful in a live hunt (as opposed to an online one). Running teams have a good amount of control over unlock order and can plan locations that make sense in terms of geography, allowing teams to minimize the amount of backtracking that they have to do. For walking hunts in particular, many trails tend to take teams in a loop so that at the end of the hunt they are near the transportation option that they chose to arrive to the hunt with.

However, there are some drawbacks. First, the number of puzzles that are open at any given time is generally one. This typically restricts the team size to at most four to six people, or else parallelizing puzzle solving becomes difficult for some types of puzzles. Additionally, puzzles cannot be very difficult, or else the puzzle may end up as a bottleneck for many teams. There are several ways to mitigate this. Hints are usually given at a fairly liberal rate, in the timespan of tens of minutes to an hour for a given puzzle. Some trails allow teams to skip a puzzle entirely, although this usually incurs a large time or score penalty. Because the running team usually does not staff every location for the entire duration of the hunt, they may be forced to tell teams to move to the next location without solving the previous puzzle.

Strategies
For physical hunts, there is also a bit of "metagaming" available, as teams may vaguely track their progress against other teams based on when they arrive at a particular puzzle station. Online hunts of this format are rare, but if there is a live solve leaderboard (which may not be the case), this serves as a precise indicator of progress, as unlike in other hunts a team that has more solves is strictly ahead of another team with fewer solves, without any complicating factors like skipping puzzles once a meta is solved. ClueKeeper hunts in particular do not count time spent in transit between locations, only counting time starting when they receive the puzzle (after entering a start code into the app). Therefore, some teams choose to take long breaks in between puzzles (taking care to not fall too far behind such that the puzzle station closes).