Design Fundamentals of Stealth Gameplay in the Thief series

Design Fundamentalsof Stealth Gameplayin the Thief series Randy Smith rsmith@ionstorm.com Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Disclaimers • I didn’t design Thief’s gameplay • Doug Church • Marc LeBlanc • Tom Leonard • Paul Neurath • This is about open-ended stealth gameplay. Other games mentioned are being evaluated by this standard only. • Tim Stellmach • Greg LoPicollo • Dorian Hart • etc. Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

What is stealth in Thief ? • Goal = move through space • Steal • Blackjack • etc. • Failure = AI state becomes “alert” • Combat • Fleeing • Pick lock • Pick pocket Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

How does the AI become alert? • The player has detectability • Visibility (light gem = feedback) • Audibility • The AI has senses • Seeing • Hearing • The overlap between player detectability and AI senses… • …is where the AI becomes alert or not • …is where stealth happens Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

What is this lecture about? • It is about stealth gameplay • Player movement through space • Player detectability • AI Senses • AI State • It is not about: • Goals (such as stealing) • Consequences (such as combat) Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Let’s design a stealth game! You are a thief in a medieval city. There is a mansion in the distance, full of loot. A wall separates you from the mansion, and a guard patrols in front of the gate. A torch nearby spills light across the area. Do you: A) Wait until the guard has his back turned and run through the gate. B) Put out the torch with a water arrow. C) Sneak up on the guard through the shadows and blackjack him. Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

More stuff this lecture is about: • It is not about: • Stealth flavoredgameplay • How gameplay is qualified (what makes stealth gameplay stealth gameplay??) • What is the definition of “open-ended” gameplay? • Discrete interaction • It is about: • Player expression • Analog interaction Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Major concepts for this lecture • Discrete Interaction Structures • Exemplified by Choose-Your-Own-Adventure books • Analog Interaction Structures • Exemplified (for the sake of this presentation) by Quake or other FPS Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Qualities of Discrete Interaction Structures • Finite, enumerable choices offered to the player. • Player must choose one of the available options, not something in-between, not invent their own thing. • Designer must explicitly create all interaction for the player. • Should be called “Choose Someone Else’s Adventure” Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

What are Analog Interaction Structures? • Rough Definition: A collection of player-influenced, interacting game systems • An abstract design tool for (de)constructing open-ended gameplay and analyzing relevant data • A “unified theory” of existing thought: • Simulation vs. Emulation • Player Tools • Partial Failure • Feedback • etc. Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

What are analog interaction structures NOT ? • The only way to think about, construct, or deconstruct any type of gameplay • Necessarily the most useful tool for the job • A ton of brand new thought Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

A Useful Metric • To what extent can the designer predict the player’s experiences? • A lot, the player can not take any action the designer did not explicitly implement and intent Discrete Interaction • Not much, really, the player has near-infinite ways to overcome the game’s challenges  Analog Interaction Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Analog Expression: Player Movement in Quake • Data relating to player movement: • Player location (X,Y,Z) • Player orientation (H, P) • Player velocity vector • Player acceleration vector • Player expression: • Accelerate in various directions • Look right, left, up, down, or combo • Some fancy movement (jump, duck, etc.) Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

What makes it “analog”? • Hey, yea! There aren’t analog variables – so theoretically, all possible states are enumerable. • ...but the player cannot “choose” their movement data. There is no “choice”. • Instead, the player uses movement tools to set or “express” their desired movement data. Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Player movement is relevant to Quake’s core gameplay • Player movement data is critical to resolving combat from moment to moment: • Orientation is how you aim weapons • Movement is how you dodge, take cover, charge, etc. • These are examples of the player expressing “higher order concepts” Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

What else does Quake have? • For both Player and Enemies: • Movement • Weapons that fire projectiles • Damage model (hit points) • Projectiles • A game world with physics simulation. • Collisions between player, terrain, projectiles. Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Components to Analog Interaction Structures • A game world that hosts interactions dictated by simulations (in Quake, physics in the 3D world) • Analog player expression (in Quake, player movement) • Analog/partial failure (in Quake, hit points) • Player tools to take arbitrary actions (in Quake, weapons that fire projectiles) Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Let’s talk about Thief already • Game world that hosts interactions dictated by simulations = 3D world, similar to Quake • Physics • Line-of-sight (LOS) • Lighting, light sources • Sound propagation, noisy surfaces Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Analog Expression in Thief • Player movement • Player location (X,Y,Z) • Player orientation (H, P) • Player velocity vector • Player acceleration vector • Player movement expression • Accelerate in various directions • Look right, left, up, down, combo • Some fancy movement (jump, climb, etc.) Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Higher Order Concepts in Expressing Stealth • Hide in shadows = move into a dark part of the world • Move silently = avoid moving over loud surfaces, move slowly Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Quake with only 1 hit point • No partial / analog failure • A lot of the data becomes much less relevant to resolving combat: • How damaging weapons are • Player’s emergent combat tactics when they are weak versus when they are healthy Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Stealth-related tools in Thief • Potions • Invisibility • Speed • Thrown tools • Flashbomb • Arrows • Water arrow • Moss arrow • Noisemaker arrow Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Analog Interaction Structure chart = a data analysis tool • Useful for thinking about data: • What data the player has input into • How data flows from system to system and eventually leads to success or failure • Drawing the chart is as much art as science • Which data boxes? • How many arrows? • Draw the chart differently to analyze the data differently Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Feedback in Thief • AI State and AI Senses • Broadcast speech • Animations • Behavior • Player Visibility / Audibility • Light gem • Listening • AI Movement • Player senses Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Level-building for Analog Interaction • Don’t create “scripts” • Don’t plan the player’s experiences for them. • Create “possibility spaces” • Populate the world with challenges • Populate the world with things that interact with the player’s tools, the simulations, manipulate the data flow • Avoid absolutes, embrace gradients Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Design new types of analog gameplay! • A game world that hosts interactions dictated by simulations • Analog player expression • Analog failure • Player tools to take arbitrary actions Design Fundamentals of Stealth Gameplay in the Thief Series, rsmith@ionstorm.com

Design Fundamentals of Stealth Gameplay in the Thief series