Timed Unlocks

Timed Unlocks is an unlock structure used in puzzle hunts. In hunts that use it, puzzles are usually arranged in a chronological list, so that when a new puzzle is unlocked it will be either at the top or at the bottom of the list. Unlike other unlock methods, when all available puzzles are solved, there won't necessarily be more unlocked automatically.

Background
Timed unlocks are a common aspect of 'Australian Style' hunts. In these hunts, puzzles are released in batches, one batch per day, over the course of a particular period of time. Hunts like MUMS, SUMS, and CiSRA all use the Australian Style of timed unlocks.

Hunt Application
Timed Unlocks can be done either as a primary unlock mechanism or as a supplemental unlock mechanism.

As a primary unlock mechanism, Timed Unlocks are not overly common. They can be done in batches (as in Australian Style), or one-by-one, but the key is that the only way to unlock new puzzles after solving all of the ones that are available is to wait. Regardless of how fast or slow someone solves a day's puzzle(s), everyone waits the same amount of time for the next drop.

Timed Unlocks are much more common as a supplement to another unlock mechanism (like the default per-solve unlocks). As a supplement, it essentially acts as a backup to ensure that solvers who are not on track to unlock everything by the end of a hunt get to see everything the hunt has to offer regardless of their solving speed. While these may be seen as 'pity' unlocks by some, they've become quite popular in large hunts with relatively small duration as a way of balancing them out. Alternatively, some hunts have taken it upon themselves to include bulk timed unlocks as an opt-in, so that teams don't feel 'pitied' by the organizers.

Examples

 * - The first edition of GPH used timed batch unlocks, similar to Australian Style hunts. However, unlike most Australian hunts, this one contained multiple metapuzzles, which were also released as a batch of five on the sixth day of the hunt.
 * - This hunt took place over the course of a month, with a single new puzzle coming out every day, up until a finale on the final day that involved several metapuzzles.