1. Introduction to Interactive Fiction CS 370 Spring, 2003

2. Overview What is interactive fiction? Plot structure Settings Characters Modeling in INFORM

3. Traditional fiction Control vested entirely in the author –What happens when in the imagined world –What the reader finds out about it, and when. –Reader can only choose to stop or continue Two categories of relationships between events –Events in the (imagined) world –Events in the narrative about the imagined world.

4. Interactive fiction Author shares control –Player, not reader Conflicting demands –Player wants freedom to do and see whatever they find interesting –Author wants to tell their story

5. Player freedom makes author’s job much harder The imagined world must be modeled in software The model must be rich enough to –support the story –give the player the appropriate level of freedom The model must be simple enough to –be implementable with the author’s resources –keep the player from getting lost

6. Idea of plot structure Characterize a work by collection of events that occur in it and the relationships between them –Events can include changes in a character’s beliefs or emotions –Even in linear text, the relationships can be subtle e.g., the slow realization of a jailer that holding political prisoners is wrong.

7. Plot structure Composed of events in narrative –not always corresponding directly to events in imagined world –For interactive fiction, tends to be tighter identification between them because the player is always center-stage. Different outcomes of events can lead to complex structure in interactive fiction

8. Plot structure in traditional fiction Freeble is born Freeble Triumphs! Freeble endures grueling upbringing Freeble makes way into the world Freeble has setbacks Freeble gets deeper into trouble Freeble struggles; tide turns

9. Linear plots can be found in interactive fiction Freeble is born Freeble Triumphs! Freeble endures grueling upbringing Freeble makes way into the world Freeble has setbacks Freeble gets deeper into trouble Freeble struggles; tide turns Freeble dies

10. IF supports more complex plot structures Freeble is born Freeble Triumphs! Freeble endures grueling upbringing Freeble joins cult Freeble has setbacks Freeble gets deeper into trouble Freeble struggles; tide turns Freeble becomes drug dealer Freeble becomes Amway dealer

11. Other Extreme: Exploratory environments/“software toys” rely on player-generated plots Your favorite project here Use cropduster on town Evolve Carniferns to intelligence Make 1,000,000 credits Build city with arcologies

12. Tradeoff: Freedom for narrative coherence All the paths need to form a coherent story Every downstream event has to consider the different ways it can be reached If there is a preferred ending, how far should the player be allowed to go down an unrecoverable path?

13. Events in interactive fiction Typically the player doing something or achieving something Player’s choice of actions can lead to different outcomes Changes of belief result from player’s reflection on the consequences of their actions –Telling someone they’ve had a moral conversion typically isn’t effective.

14. Events as puzzles “An adventure game is a crossword at war with a narrative” –Graham Nelson, author of INFORM Well-designed puzzles bring the reader deeper into the game –Encourages thinking harder about the imagined world –Provides satisfaction when solved –Provides criterion for moving through the plot

15. Settings Imagined world must be represented in software somehow Implementation technology choices interact tightly with modeling choices Difficulty of modeling still major drawback in authoring interactive fiction

16. Text-based IF Classic version, due to mainframe limitations Settings described by evocative text Objects in world modeled by behaviors that produce text indicating state changes Movement, actions specified by restricted natural language.

17. Graphic adventure games Examples: Ultima series, X Quest... Rely on 2D images or 3D rendered environments to model settings Use mouse to select objects to act upon, menu to determine action –Sometimes simple text parser provided as well Eye candy appealing, but more expensive to create

18. Simulations with plots Examples: Wing Commander series, Archimedian Dynasty Settings are combinations of simulator scenarios and cut scenes (2D, 3D, or video) Performance in simulator determines movement in plot structure

19. Endo / \\ (2) (3) McAuliffe Gateway Progress screen one...... / \\ / \\ / \\ / \\ (4)===>===(5)---<---(6) Gimle Brimstone Cheng-Du Progress screen two...... \ / \\ // \ / \\ // (7) (8) Dakota Port Hedland Progress screen three.... / \\ / \\ / \\ / \\ (9)===>===(10)--<--(11) Kurasawa Rostov Hubble's Star Progress screen four..... \ / \\ // \ / \\ // (12) (13) Venice Hell's Kitchen (victory) (defeat) Wing Commander 1’s plot structure

20. RPG/adventure hybrids Examples: Privateer series, Elite Range of settings similar to simulator-based games Plot structures lurking in world, but also allows open-ended play Automatically generated scenarios keep things interesting. –Ideally

21. Characters A critical aspect of interactive fiction The most complex aspect of interactive fiction The aspect most need of improvement –New AI advances hold great promise here –Human-like characters is a Holy Grail of the computer game industry

22. Characters in text-based IF NPC = “Non-player character” Simple stimulus-response systems –Player asks about a topic, gets canned reply, perhaps with randomness in responses –Player orders NPC to do something, may or may not do it, according to programming Finite state machines –Behave differently based on player’s actions, other events in game

23. Characters in other interactive fiction In 2D image settings, only interaction is conversation. –Scripting similar to text-only games In others, richer models of interaction used –Current technology is far from having generally smart characters –Lots of tricks used to make characters seem realistic

24. Let’s kick the tires

25. Modeling in INFORM Provides object-oriented language suitable for writing text-based interactive fiction C-like syntax, but object-oriented Libraries for interactive fiction idioms included –and can be extended, as can the parser Best way to learn is to build a piece of interactive fiction…

26. Example: Twonky Island The prototype The code so far

27. Your own work of fiction You will write a short story in INFORM. –HW2: Story bible and half of the objects required –HW3: Rest of objects, full story delivered –HW4: Play testing two other people’s stories Specifications will be on the web tonight Discussions on-line through class newsgroup as needed