Those interested in puzzle typology in IF may also want to try Recruit, by Mike Sousa, which is sort of a sampler pack of different types of IF puzzle. Not all the examples are equally compelling, but it makes an interesting study.

I used to have a list of especially large and difficult games, but it has since gotten easier to look these things up using other resources. See: games on the IF Scoreboard which take 12-20 hours to play, the “Puzzle-fest” genre on the IF Scoreboard.

Puzzle Types

Games in this category typify some interesting type of puzzle in a relatively pure form.

Mystery and Research Puzzles. The action of the game centers on putting together information (whether or not the actual genre of the game is considered “mystery” or not).

  • Anchorhead, Michael Gentry. A marvelously designed horror game where the player gradually assembles information about what is going on and why. [My Review]
  • Christminster, Gareth Rees. There are bunches of non-research-related puzzles in the game, but quite a few bits do turn on knowing where to look what up.
  • Slouching Towards Bedlam, Daniel Ravipinto and Star Foster. Early parts of the game require the player to sift through infodumps for the important information, then figure out how to apply that information.

Diagnostic Puzzles. The challenge is to collect enough information about a problem to identify an item or type.

  • Cheiron, Sarah Clelland and Elisabeth Polli. An educational medical puzzler requiring the player to identify illnesses by examining patients.
  • When in Rome 2, Emily Short. A single character with randomized characteristics, whose species the player must identify through observation and interaction.

Resource Management Puzzles. Game requires you to assign the use of a limited resource (time, space, money, etc) carefully in order to win. (See also Timing and Sequencing Puzzles.)

  • One Week, Papillon. Choose-Your-Own-Adventure, implemented in TADS. You have a limited amount of time in the course of your week, and must divide it between study, social activities, and earning money at your job; what you decide to do determines what resources you have later on to buy a prom dress, whether or not you have a date for said prom, and how well you do on your SATs. [My review]
  • When Help Collides, J. D. Berry. A multi-part game that includes some things that are not exactly normal IF, especially a Geisha simulator program, in which your task is to schedule your time properly for best effect. (You can play just the geisha portion of the game, if you wish, by typing a code at the opening prompt of the game. See the accompanying text file for information.) [Discussed somewhat in my review of One Week]
  • Hell: A Comedy of Errors, John Evans. You are a demon, in hell; your job is to make use of various torture devices to extract the maximum possible suffering from the souls assigned to your care. It seems like it ought to be more entertaining than it actually is, largely because there is not enough variety in the description and not enough feedback about what’s going on. However, it does implement an interesting system wherein you are able to “dig” new rooms — creating a dynamic game map as you go along.

Geographical Puzzles. Puzzles involving management and manipulation of space. A common example of this puzzle type is the maze: simple mazes are often deprecated in modern IF criticism because they tend to be easy but boring to solve. However, some games do offer interesting variations in which the solution requires noticing some special fact about the environment or applying a non-obvious method to solve.

  • Enchanter, Infocom. Through magic, the player can influence the interrelation of rooms in order to gain access to special areas. See also the Carousel Room in Zork II, the Royal Puzzle in Zork III, and the hedge maze in Curses.
  • Delightful Wallpaper, Andrew Plotkin. The puzzle in the first part of the game involves traversing the available geography in a specific sequence in order to make all the space available. See also the Bank of Zork in Zork II and the wine cellar in Savoir-Faire.

Timing and Sequencing Puzzles. The player may know roughly what needs to be done, but the challenge is to get actions into the right order or optimize performance so that they occur quickly enough.

  • All Things Devours, half sick of shadows. A time-travel puzzle in which the player must coordinate a sequence of actions to achieve the desired results with no conflicts. See also the entirety of Möbius by J. D. Clemens and the chute puzzle in Sorcerer.

Cryptographic Puzzles. The player must solve a cryptography challenge, either by himself outside of the game or by using some in-game cryptographical mechanism to resolve it.

  • Christminster, Gareth Rees. Cryptogram that can be solved with a password in-game.
  • Jigsaw, Graham Nelson. Requires the player to make use of a simulated Enigma machine.
  • Labyrinth, Samantha Casanova Preuninger.

Riddles. The player is asked to think of the solution to a riddle in order to move forward. These can be arbitrary and difficult to solve and many are now deprecated.

  • Zork II, Infocom.

Word and Language Puzzles. The words of the narrative are important as more than just the representation of an underlying world model, so that the player isn’t interacting as much with a simulated environment as with the description of that environment.

  • The Edifice, Lucian Smith. Contains the famous Nalian language puzzle, in which the player must learn to communicate with a Stranger in the words of his own language.
  • The Gostak, Carl Muckenhoupt. The entire game is written in an unfamiliar language — or perhaps just a dialect of English in which all the vocabulary is different — and a large portion of the challenge is in figuring out enough about what’s going on to be able to interact with it.
  • Letters From Home, Roger Firth. A work of IF which has more than usual in common with crosswords, in which the player moves around collecting items that actually are letters.
  • Ad Verbum, Nick Montfort. A game that turns on wordplay and the expression of commands rather than/as well as on the underlying mechanics of the world.
  • Goose, Egg, Badger, Brian Rapp. Toys with the way in which some words are both nouns and verbs in English.
  • Puddles on the Path, Anssi Raisanen. Solutions to the puzzles in this game require the player to remember and use famous proverbs and sayings. [My Review]

Approaches to Puzzle Design

Multiple Solutions. Many or even most puzzles in the game offer more than one viable solution. This feature often (but not always) goes hand-in-hand with a simulationist approach to world modeling, since rigorous simulationism makes it possible to offer the player solutions which haven’t even occurred to the author.

  • Wishbringer, Infocom. The game is full of puzzles that have an “easy” and a “hard” solution, so once you’ve solved it one way you can go back and solve it the other.
  • I-0, Adam Cadre. Most puzzles in the game allow for multiple approaches and solutions; the solutions you choose also to some extent characterize the player.
  • Firebird, Bonnie Montgomery. An easy game set in the world of Russian fairy tales, designed to be accessible to younger or less puzzle-adept players. See also Mother Loose by Irene Callaci.
  • Erudition Chamber, Daniel Freas. The player is being tested for his attitudes towards puzzle-solving, and is put in a series of situations which he can resolve any of four ways.
  • Scavenger, Quintin Stone. Decisions about what to bring along early in the game determine what resources the player will have available later on. See also Moments Out of Time by L. Ross Raszewski.

Adjustable Puzzle Difficulty. Games which allow the player to determine how hard he wants to work. (Usually has to be set at the beginning.) These games approach the adjustable puzzles in different ways: in some cases, choosing an easier version means some puzzles are already done for you; in others, the same puzzles occur but are simplified in the easier settings.

  • Inevitable, Kathleen Fischer. Comes in several difficulty levels, from which the player may select freely at the outset. See also Game Producer! by Jason Bergman.
  • City of Secrets, Emily Short. Has a “standard” difficulty and also a “novice” difficulty; if the player has too much trouble with the beginning of the game, it will automatically set itself to novice.
  • Cowboy Blues, David Whyld. If you choose the easier form of the game, some of the puzzles are done for you, but you can’t achieve full points.
  • Dreamhold, Andrew Plotkin. Since the game is designed as a tutorial for newbies, but intended also to be enjoyable to experienced IF players, Dreamhold offers a choice of novice and expert difficulty levels, as well as a Tutorial Voice that can be turned off. For the most part this works reasonably well, though there are a few pieces of the landscape that only have a purpose in the Expert puzzle mode, and may seem unnecessary to the novice player.

Structural Considerations

Single-Puzzle Games. Game turns on resolving one major puzzle. There may be a number of subcomponents to this puzzle.

  • Tyler’s Great Cube Game, Tyler Binden. Involves a labyrinth set inside a giant Rubik’s Cube. See also Labyrinth, Samantha Casanova Preuninger.
  • Rematch, Andrew Pontious. An exceptionally complex puzzle which requires many iterations to resolve. Definitely a learn-by-dying game, taken to its ultimate highest expression. [My Review]
  • Lock and Key, Adam Cadre. A one-puzzle game that relies on an enhanced interface to make it playable. In Glulx, with rather nice pictures. Must be replayed multiple times.

Non-game Puzzles. Puzzles that are more or less devoid of any kind of surrounding story and exist purely as an exercise.

  • Schroedinger’s Cat, James Willson. There is no narrative framework at all, and no ending either. It is up to the player to decide when he has successfully figured out how the game environment works.
  • In the Spotlight, John Byrd. A simple physical problem which the player can solve, without any kind of surrounding story. See also Koan by Esa Peuha and No Room by Ben Heaton.

Graded Success. Instead of making the player solve all the game puzzles to win, these pieces assign a range of endings (from abject failure to best-possible-outcome) depending on how well the player did and which problems he solved.

  • Paint!!!, David Whyld. The challenge is to lead a work crew to get an office painted, despite a series of wacky and irritating disasters. The more of the disasters you overcome, the better the job you do on the office, and the greater your final payoff.
  • Damnatio Memoriae, Emily Short. The player character is about to be arrested and must get rid of all the evidence that points to him. There are a number of possible solutions and degrees of success; depending on his choices, the player can survive but cause trouble for his family members and friends, or lose things of value to him.

Win-on-the-first-try. The player is discouraged from ever UNDOing a move or restoring a saved game (other than as a way to take a break from play); instead, he is supposed to try to win on the first play-through.