Game Design -

Game Design -

Interactive Media and Game Development Game Design Outline Selecting Features Level Design Core Design (next) What Next? Note! First Then, have

Need Problem too many ideas! Work on core mechanics (movement, shooting, etc.) Get bugs worked out, animations and movement smooth prototype with solid core mechanics tweaked some gameplay so can try out levels 25 levels Rest of features If dont have enough, show it to some friends and theyll give you some Selecting Features Types Player can use

Abilities (attack moves, swimming, flying) Equipment (weapons, armor, vehicles) Characters (engineer, wizard, medic) Buildings (garage, barracks, armory) Player must overcome Opponents (with new abilities) Obstacles (traps, puzzles, terrain) Environments (battlefields, tracks, climate) Categorizing may help decide identity Ex: Game may want many kinds of obstacles, or many characters. What is core? Tips on Vetting

Pie in the Sky Starting an Arms Race One-Trick Ponies The Koala picks up the jetpack and everything turns 3d and you fly through this customizable maze at 1000 m.p.h Beware of features that are too much work Dont always choose the easiest, but look (and think) before you leap And dont always discard the craziest features you may find they work out after all Once the Koalas get their nuclear tank, nothing can hurt them. Sweet! No, wait If you give player new ability (say tank) theyll like it fine at first

But subsequently, earlier challenges are too easy You cant easily take it away next level Need to worry about balance of subsequent levels On this one level, the Koala gets swallowed by a giant and has to go through the intestines fighting bile and stuff Beware of work on a feature, even if cool, that is only used once Outline Selecting Features (done) Level Design (next) Core Design Learning Curves Stage 2 Stage 1 Skill Stage 3

Practice (Time) Stage 1 Players learn lots, bug progress slow. Often can give up. Designer needs to ensure enough progress that continues Stage 2 Players know lots, increase in skill at rapid rate. Engrossed. Easy to keep player hooked. Stage 3 Mastered challenges. Skill levels off. Designer needs to ensure challenges continue. Difficulty Difficulty Curves Stage 1 Stage 2 Easy

Medium Hard Practice (Time) Maintain Stage 2 by introducing new features! Too steep? Player gives up out of frustration. Too shallow? Player gets bored and quits. How to tell? Lots of play testing! Still, some guidelines Guidelines

Decide how many levels (virtual or real) Divide into equal groups of EASY, MEDIUM, HARD (in order) Design each level and decide which group All players complete EASY. Design these for those who have never played before Most can complete MEDIUM. Casual game-players of this genre Good players complete HARD. These are designed for yourself and friends who play these games. If not enough in each group, redesign to make harder or easier so about equal number Play all and arrange in order, easiest to hardest Test on different players (friends and family, but enough in each category) Tweak according to outcomes of test Outline Selecting Features (done)

Level Design (done) Core Design (next) Implementing Gameplay (1 of 2) Choices must be non-trivial, with upside and downside If only upside, AI should take care of it If only downside, no-one will ever use it Note, this is only regarding game theory Ex: Could have ray gun that plays music. Cool, but soon gimme the BFG Ex: Nintendos Smash Bros has Taunt ask: what for? Ask: other examples from popular games?

Gameplay value when upside and downside and payoff depends upon other factors Ex: Rohan horsemen, but what if other player recruits pikemen? Ex: Bazooka, but what if other player gets out of tank? Implementing Gameplay (2 of 3) Should be series of interesting choices Ex: Use of health potion now may depend upon whether have net for capturing more fairies Having net may depend upon whether needed space for more arrows for bow

Needing arrows may depend upon whether killed all flying zombie bats yet Hence, well designed game should require strategy Game must display complexity But doesnt mean it must be complex! Dont make too many rules. Less if more. Real world example: termites place one piece of mud. Results in hive, with cooling vents, etc. Avoid Trivial Choices Horsemen Archers Pikemen Transitive, not so interesting Horsemen Archers Pikemen Horsemen (picture) Ask: what game does this look like? (rock-paperscissors)

Intransitive, more interesting Ex: from LOTR Battle for Middle Earth Horsemen fast, get to archers quickly with lances Pikemen spears hurt horsemen bad Pikemen slow, so archers wail on them from afar Dont want to hardwire. Sometimes A way better than B, sometimes a bit better, sometimes worse The answer should depend upon the game situation, weather, terrain, time also what opponent is doing Ensuring Interesting Choices Interesting choices require good judgment on the part of the player Correct choice must vary with

circumstances Aim as designer, ensure circumstances dont stagnate and have only one right way to win No method for finding best choices Thats where creativity comes in (art) Still, some tips Toolbox of Interesting Choices Strategic versus Tactical Supporting Investments Versatility Compensating Factors Impermanence Shadow Costs Synergies Strategic versus Tactical (1 of 3)

Strategic choices affect course of game over medium or long term Tactical choices apply right now Ex: build archers or swordsmen (strategic) Ex: send archers or swordsmen to defend against invading force (tactical) Strategic choices have effect on tactical choices later Ex: if dont build archers, cant use tactically later Strategic versus Tactical (2 of 3) Ex: StarCraft Strategic choice: 1 ) upgrade range of marines, 2) upgrade damage, or 3) research faster fire Which to choose?

If armored foes, Protoss Zealot, more damage If fast foes, Zerglings, maybe faster fire Other factors: number of marines, terrain, on offense or defense Strategic versus Tactical (3 of 3) Ex: Warzone 2100 (ask: who played?) Build factories to spawn war machines If build in level, then spawn quickly but factory only used for that level If build at base, spawn slowly (have to ship to front lines) but factory can be used in subsequent levels Lesson: Good gameplay should have different choices leading to different kinds of payoff Reduces the risk of trivial choices

Increase scope for good judgment Supporting Investments Often game has primary goal (ex: beat enemy) but secondary goals (ex: build farms for resources) Some expenditures directly impact primary goal (ex: hire soldier), while others indirect (ex: build farm) called supporting investments Primary goals are one-removed Ex: improve weapons, build extra barracks Supporting goals are two-removed Ex: build smithy can then improve weapons Ex: research construction lets you build smithy and build barracks (two and three removed)

Most interesting since strategic Payoff will depend upon what opponents do Versatility (1 of 2) Rule of thumb is to ask what is best and worst about choices: 1) 2) 3) 4) This This This This

move does most damage, but slowest move is fastest, but makes defenseless move best defense, but little damage neither best nor worst, but most versatile Most should be best in some way Versatile good for beginners flexibility (against unpredictable or expert opponent) Versatility (2 of 2) Ex: beam can mine asteroids and shoot enemies Versatility makes it good choice Speed is common way for versatility Dont make fast units best If a versatile unit is also cheapest and most powerful no interesting choice

(See Compensating Factors, next) Compensating Factors Consider strategy game where all units impeded by some terrain Ships cant go on land, tanks cant cross water, camel riders only in dessert Assume flying unit that can go anywhere (Ask: how to balance?) 1) 2) 3) 4) Make Make

Make Make slow weak, easily destroyed low surveillance range (unrealistic) expensive Note, last choice common but uninteresting since doesnt change tactical use Choice should be clear to player. Dont make a gamble before they know. Ex: pick troops (cold weather) then find in jungle Impermanence (1 of 2) Some permanent (ex: you get to treasure first), others not (ex: I got storage near mine, but you can grab it off me)

Really, another kind of compensating factor I.e. impermanence can compensate for something being really good Can be used for interesting choices Ex: choice of medium armor for rest of game or invulnerable for 30 seconds? Advantage (or disadvantages) can be impermanent in number of ways: Impermanence (2 of 2) (Examples mostly from Magic the Gathering Battlegrounds) Can be destroyed (enchantments, ex: gratuitous violence makes units tough, but can be destroyed) Can be stolen or converted (ex: threaten steals

or converts enemy for short time) Can be applied to something you dont always have (ex: goblin king gives bonus to goblins, but must have goblins) Certain number of uses (ex: three grenades, but grenade spamming) Last for some time (wears off, ex: Mario invulnerable star) Common in games, but deserves special attention Shadow Costs (1 of 2) In a game, continually presented with costs and trade-offs. But not all direct. Ex: soldiers for gold, but need armory first for weapons and barracks for soldiers Called shadow costs for supporting investments Can make flow chart mapping shadow

costs Shadow Costs (2 of 2) Ex: Age of Mythology has wood and food. Food is inexhaustible, wood is finite Charioteer Costs 60 wood, 40 food and 40 seconds to spawn Shadow costs vary over game Early on, food and wood expensive, spawn doesnt matter Mid-game, much food and wood, spawn makes it harder to pump out new units End-game, no wood, spawn is priceless Use variability to add subtlety to game. Vary environment and vary shadow costs (ex: more trees to vary cost of wood)

Challenge for level designer Expert players will appreciate Synergies (1 of 2) Synergies are interaction between different elements of players strategies (note, terms may be different than ch 2.2) Positive Feedback Economies of Scale the more of one type, the better (ex: wizards draw strength from each other) Economies of Scope the more of a set, the better, or advantage of combined arms (ex: trident and net, infantry and tanks)

Negative Feedback Diseconomies of scale first is most useful, others have less benefit (ex: diminishing returns from more peasants entering a mine since get in each others way) Diseconomies of scope (ex: mixed troops go only as fast as slowest) Synergies (2 of 2)

Ideally, all go together at once, but can emphasize Ex: Chess is a game of positive feedback Small advantage early on, exploited to crushing advantage Game of negative feedback needs other ways to keep interesting Ex: trench combat makes a catch-up factor, or as get far from base, supply long grows, game lasts a long time Ex: Super NES NBA Jam catch up setting as an equalizer Be aware of each Review: Use Tools from Toolbox of Interesting Choices

Strategic versus Tactical Supporting Investments Versatility Compensating Factors Impermanence Shadow Costs Synergies Groupwork: Use 1-2 in a game about graduating from high school. Discuss. AI and Games

Opponents that are challenging, or allies that are helpful Unit that is credited with acting on own Human-level intelligence too hard But under narrow circumstances can do pretty well Ex: chess and Deep Blue Artificial Intelligence Around in CS for some time Games a special niche (needs to be realtime) AI and Games Must be smart, but purposely flawed

Must perform in real time (CPU) Configurable by designers Lose in a fun, challenging way No unintended weaknesses No "golden path" to defeat Must not look dumb Not hard coded by programmer "Amount" and type of AI for game can vary RTS needs global strategy, FPS needs modeling of individual units at "footstep" level RTS most demanding: 3 full-time AI programmers Puzzle, street fighting: 1 part-time AI programmer Group Exercise Consider game where hero is in a

pyramid full of mummies. Mummy wanders around maze. When hero gets close, can sense and moves quicker. When it can see hero, rushes to attack. If wounded, flees. What states can you see? What are the transitions? Can you suggest Game Maker appropriate code? Finite State Machines (1 of 2) S ee Enem y W ander A tta c k N He a lt h

N o E nem y o En y Lo w em F le e Abstract model of computation Formally:

Set of states A starting state An input vocabulary A transition function that maps inputs and the current state to a next state Finite State Machines (2 of 2) S ee Enem y W ander A tta c k N He a lt h N o E nem y o En y

Lo w em F le e Most common game AI software pattern Natural correspondence between states and behaviors Easy to understand, program and debug Completely general to any problem Problems Explosion of states Often created with ad-hoc structure

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