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Interactivity & the Core Game Mechanic

Foundations of Interactive Game DesignProf. Jim Whitehead

February 6, 2008

Today’s Assignment

• Work Breakdown and Schedule‣ Due Today

• Have exams and game concept documents‣ Come up on stage after class to retrieve

Upcoming Assignments

•Busy week next week‣ Partially Operational Game Prototype

❖ Due Friday, February 15

❖ Need to have started your game

❖ Need to have at least some things working already

❖ Demonstration that you have spent at least 5-10 hours on your game already

‣ Progress Report❖ Also due Friday, February 15

❖ An update on where things stand in your schedule

❖ Is your project completing tasks on schedule, or falling behind?

Game Design Workshops

• Game Maker‣ Wednesdays, 6-8pm

‣ Engineering 2, room 180 (Simularium)❖ Enter on plaza level between E2 and JBE

• RPG Maker‣ Wednesdays, 5-7:15pm

‣ Engineering 2, room 280❖ 2nd floor, on front of building, on driving circle/Communications end (right side,

east end) of the building

❖ Arrive by 6pm to avoid external doors locking

❖ Knock on nearest door if late…

• CS 20/C# and XNA Game Studio Express‣ Thursdays, 4:30-7pm‣ Engineering 2, room 399 (third floor, by elevators)

Interactivity• What was the essential element of computer games that made

them so compelling, and allowed the industry to grow so quickly? ‣ Not video, audio, or text by itself, since these all predated video games by

many years

• Interactivity! ‣ Computing power makes this interactivity possible.

• “Just as the schwerpunkt of computers is processing, so too the schwerpunkt of all software is interactivity—and this goes double for games.”

• “Graphics, animation, sound, and music are all necessary to gaming, and they’re all important, but they’re not the schwerpunkt. Interactivity (sometimes called “gameplay”) is the real schwerpunkt of games.”

‣ Chris Crawford on Game Design, p. 74.

‣ Schwerpunkt: focal point, or, concentration of effort point, or, central point of attack

Definition of Interactivity

• Crawford uses a conversational metaphor • Interactivity is, “a cyclic process in which two active

agents alternately (and metaphorically) listen, think, and speak.” (p. 76)

• In computer games, the computer takes the role of one agent, and hence interactivity for video games becomes: ‣ “How can we program the computer to be an entertaining

conversational (metaphorically speaking) partner?” (p. 77)

‣ Computer must ❖ Listen well

❖ Give the player the opportunity to say anything relevant to the situation

❖ Must think well

❖ Must speak well

Interactivity Feedback Loop

• Can view a computer game as a kind of control system‣ Game creates output

‣ Player reacts to this output by making decisions and taking action❖ This generates one or more inputs

‣ Game reacts to these inputs, creating more outputs

game creates output

player makes internal decision

player takes action

Rules of Play, p. 316

High Interactivity

• What is high and low interactivity in a game? ‣ Is a fast-paced action game more interactive than a complex, slow-

moving strategy game?

‣ Not necessarily. If two people talk quickly, does that make their conversation more interactive?

• High interactivity comes when both sides are engaged in high-quality listening, high-quality thinking, high-quality speaking.

Assessing Interactivity in a Game

• Crawford states that you can estimate the interactivity level of any game by asking three questions: ‣ How much of what the player might desire to say does the game

permit the player to actually say?

‣ How well does the game think about the player’s inputs?

‣ How well does the game express its reactions?

Applying the Questions

• Fast-paced action game: ‣ Game allows player to say a limited number of words (move up,

down, left, right, fire, etc.)

‣ Player can say these words quickly

‣ Processing is simplistic: just move around on a map

‣ Expressiveness is complete, within the very limited confines of the world.

‣ Conclusion: small amount of interaction

Applying the Questions (2)

• Civilization ‣ Pace is slower, but player has wide range of things they can express

‣ Game executes complex set of algorithms.

‣ Listening and thinking are much deeper in this game

‣ Expressiveness is also quite high – many possible pieces to move, possible interactions among pieces

‣ Conclusion: Civilization is clearly a very interactive game

• OK, so are real time strategy games like Age of Empires or Empire Earth more interactive than Civilization?

Graphic Realism

• Crawford lists as a common mistake, “obsession with cosmetics” (p. 107)

• Five common motivations for putting good graphics and sound in a game: ‣ To further the gameplay

‣ To permit the player to show off the superior cosmetic capabilities of his new computer

‣ To show off the superior technical prowess of the programmer

‣ To keep up with the competition

‣ To provide the player with images and sounds that are intrinsically pleasing

• Crawford: The first reason is the only good reason for pursuing cosmetics.‣ Agree or disagree?

Process Intensity vs Data Intensity

• Process intensity is the degree to which a program emphasizes processes instead of data. ‣ Process is algorithms, equations, branches

‣ Data is reflected in data tables, images, sounds, text

• Analogies ‣ Language: nouns vs verbs

‣ Economics: goods vs services

‣ Computers: bits and cycles

Crunch per Bit Ratio

•“Because process intensity is so close to the essence of ‘computeriness,’ it provides us with a useful criterion for evaluating the value of any piece of software. That criterion is a vague quantification of the desirability of process intensity. It uses the ratio of operations per datum, which I call the crunch per bit ratio.” (Chris Crawford on Game Design, p. 89)

Core Game Mechanic

• To have interactivity, must have interaction from player‣ The player performs some action or actions....

‣ ... that intervene in the game world.

‣ Usually, one or more of these actions occurs very frequently, and is the dominant activity of the player

‣ This is the game’s core mechanic

• Core Game Mechanic‣ The essential play activity players perform over an over again

❖ Rules of Play, p. 316.

‣ When designing a game, an important question to resolve is:What does the player do?

‣ Your design is in trouble until you can crisply answer this question

❖ ...and the answer sounds like fun

Examples of Core Game Mechanic

• Breakout‣ Player turns knob on controller (or move lever of joystick) to move

paddle left and right

‣ Choose where ball hits on paddle to control movement of ball

Examples of Core Game Mechanic (2)

• Most platformer games‣ Player moves left and right, and jumps

‣ Avoid moving enemies

• Core game mechanic isn’t all of the kinds of interactions a player may have with a game‣ More focused: only the most frequent and important interactions

‣ In Kirby’s Adventure (NES), in additionto the typical moving and jumping,the core mechanic includes inhaling

Examples of Core Game Mechanics

• For most shmups, core game mechanic is:‣ Move to avoid enemies and position ship

‣ Firing at enemies

‣ Collecting powerups

‣ Different games can alter this.❖ In Radiant Silvergun,

part of the core mechanic is selectingwhich weapon to use

Perfect Cherry Blossom

Core Mechanic Discussion

• What is the core game mechanic in the following games?‣ Guitar Hero II

‣ Mass Effect

‣ Halo 2/3

‣ Ratchet & Clank: Future