Tie-In Puzzles

Tie-In Puzzles are puzzles either found in outside publications that are then required to solve a puzzle during a hunt (along with those hunt puzzles themselves) or puzzles that hide information required to solve said puzzle in a piece of outside media.

Background
The earliest case of a modern puzzle hunt utilizing a tie-in puzzle is the 1994 MIT Mystery Hunt, wherein the first puzzle of the hunt simply told solvers to complete that day's New York Times crossword puzzle, with important information reading down the first and last columns of the grid (all explicitly mentioned in the description of the hunt "puzzle"). Since then, however, tie-in puzzles have evolved to being more than just a redirect to an outside source, as well as having increased range of media used. This is likely due to the diversification of individuals writing the hunt, as a larger writing team increases the chances of the team having at least one person with the connections to make certain tie-ins possible.

Puzzle Application
Tie-in puzzles will always be associated to a piece of media or publication outside of the hunt they're found in. However, the way they're associated, and the amount of "puzzle" still present on the hunt website can vary.

The most classic form of a tie-in puzzle is a puzzle published outside of the hunt, such as a crossword in a major newspaper or an entry in a notable puzzle column. These types of puzzles are often timed to be released on the day of the hunt's launch, and are led to by aspects of the hunt puzzle itself, such as an intermediate clue phrase prompting a solver to "SOLVE TODAY'S X" or something similar. However, this is not a requirement, as timed release is not always possible (some publications plan their puzzle releases long in advance, and without proper connections this cannot be circumvented). Either way, cases where a puzzle that must be solved is published outside of the hunt can be called true tie-ins (i.e. both the hunt puzzle involving it and the outside publication are tie-ins)

Other tie-in puzzles are released in outside publications, but not as puzzles themselves. Instead, they will be disguised as something else that would be normal to see in that publication, like a series of advertisements or an otherwise-innocuous op-ed. The amount of content on the hunt page before departing can vary, as long as the outside content is sufficiently puzzle-y and doesn't present as an established puzzle type. These would be called hidden tie-ins.

Lastly, some puzzles will appear to be standalone until reaching an extraction step, upon which it is revealed that the answer can be extracted from a piece of non-puzzle outside media. This extraction can range from taking a particular word present in a recent edition of that media, to simply pointing solvers towards a source and leaving further extraction up to them. The key to these types of tie-ins is to have most of the hunt puzzle be present on the site, with extraction being the primary departure from the hunt space. These types of tie-in are called extraction tie-ins.

Strategies
Since the actual puzzles present in tie-ins can vary greatly, there's little that can be suggested in strategy for actually solving the puzzles themselves. However, there are strategies available to prepare for a tie-in puzzle.

If a solver is aware of popular puzzle publications (such as the ones mentioned above), it would be wise to check them on the day of a hunt's start, particularly to see if any of them have been published under a pseudonym related to the hunt (such as Ms. Terry Hunter for the MIT Mystery Hunt). If there are such puzzles, solving them prior to the hunt or while teammates are solving other puzzles may save time later should a hunt puzzle point towards the tie-in.

For non-puzzle tie-ins, such as podcasts, youtube videos, or blogs, solvers may be able to identify media that is closely associated with particular members of the hunt's writing team (a podcast they are a frequent guest on, a blog they run, etc.), and keep an eye on them leading up to the hunt's kickoff. While these types of tie-ins are not overly common, there's relatively little risk to getting involved in community members' creative projects; even if they haven't hidden any puzzles in their content, they'll surely enjoy some new viewership.