When adding a puzzle to the blackboard, try to determine whether it has any of these mechanics. Your teammates may have subscribed to notifications about these mechanics, and getting first crack at them will both optimize the deployment of the team's resources and maximize the enjoyment of its members.
This puzzle involves writing, building, or filming something, then either submitting it to HQ or asking HQ to come
inspect it. This may be the second step in a puzzle, after extracting a clue phrase like TAPE YOUR HEEL TURN or
GIVE US BIOPIC SINGING VIDEO, though it could also be the entirety of a puzzle, such as in the 2011 hunt when teams
had to build a spaceship after solving the Civilization meta-meta to unlock the Katamari round.
Any crossword, be it diagramless, blocked, or barred, in any language, with any style of clue. May include variants like entering multiple letters in some squares.
In general, a cryptic clue has two parts: a definition, and a wordplay section, each of which produces the same string. Part of the trick is to figure out which part is the definition and which is the wordplay. In some cases the clue contains only wordplay, because the definitions belong to a common category where determining the category is part of the puzzle. (For example, Deep Blue, which clues this in the flavor text with "Colors you can't define".) There are also 'variety' variants where some transformation must be applied to the clue before solving, or the solution before use. Puzzazz has a thorough guide to solving them.
A puzzle with an intricate series of steps which, if followed, produce the answer without an a-ha required, but where following the steps is non-trivial. Strictly speaking a puzzle is only a Duck Konundrum if written by Dan Katz, but other step-following puzzles like Tax... In... Space... should be classified as such because they fill the same niche.
Difficult integrations, factoring the products of large primes, Rings and Fields, or any other math that you only do when your degree is specifically in math.
A puzzle that involves creating a physical artifact by knitting or crocheting. This may be inferred from flavor, such as references to thread, yarn, needles, or hooks; or by use of Knitting or Crocheting notation.
Any puzzle where you are provided with audio files containing music. This can include puzzles where the music is transformed in some way, such as I Knew Weird Al Yankovic, and You, Sir, Are No Weird Al Yankovic where you are given newly-written parodies of songs.
Any puzzle where you have a solve logic puzzles such as Sudoku, Akari, or Bridges, or a variant of one of these, including a mashup of the rules of multiple puzzle types. (Typically any appearance of one of these puzzles must be a variant, since the standard rules require completing the grid, not extracting a clue phrase.) Many of these puzzle types were invented by a Japanese publisher named Nikoli, hence the name, but other puzzle types like Skyscrapers and Battleships should be included in this category since they will tend to require the same skills.
These typically come in the form of a paragraph or short poem, where some number of words will be replaced by placeholders. These could be number words, capital letters, THIS and THAT, or a set of words that make the poem rhyme and scan and imply the operation to be carried out. An old guide to the types of flats is at the Enigma site.
This puzzle consists of or requires an object which will be given to the team by HQ. As a result it may be difficult for remote solvers to contribute to puzzles of this type.
Geoguessr-style identification of a location from something like a streetview photo.
A puzzle which either requires knowledge of one or more programming languages, or which involves a dataset large enough that extracting the necessary data from it manually would be impractical. (For example, you could theoretically generate a WAV file for 33 RPM by hand, but probably not before the hunt ended.)
A puzzle which involves going to one or more physical locations around the MIT campus. It may be difficult for remote solvers to contribute to puzzles of this type unless the running around gathers data from which the answer, or the next step, is extracted.
A puzzle where the team must gather physical objects to present to HQ. Depending on the objects to be collected, it may be difficult for remote solvers to contribute to puzzles of this type, although for Coming To A Location Near You the objects to be collected were photos of objects with Wikipedia entries a distinct number of miles from campus, which was easier for remote solvers than onsite ones.
A puzzle that involves an Infocom-style text adventure, i.e. a text box where you type a command for your character to follow and receive a textual description of the results of that action.
A puzzle that involves a graphical video game that team members must play. This can either be a game that is provided to the team, such as Twitch Plays Mystery Hunt or Asteroids, or one where a provided level must be played in a commercial game, such as Puzzle Box.