2. Game Difficulty Again driven by target audience
BUT modifiable difficulty can widen audience
Also adds to replayability
As discussed earlier, difficulty is key for player engagement
Too easy and game is boring, no feeling of accomplishment
Too hard and game is frustrating, player is too uncomfortable to learn
Sweet spot is in the middle with regular rewards for increasing skill
There are some exceptions, eg Slot Machines
Difficulty can be static or dynamic
Why choose one over the other?

3. Static Game Difficulty
Player chooses difficulty
Give player control over their play experience
Makes it clear what “tier” player is on
Makes game more repeatable
Easy to reward more difficult play
Can be as simple as bragging rights, higher scores, etc
Generally easiest to implement.
Fixed tuning levels

4. Dynamic Game Difficulty
Game adjusts to player on the fly
“Rubber banding”
Ideally keeps everyone in the area that flow occurs
Difficult to implement/tune
Needs many levels, or continuos tuning
Can be gamed
Purposefully flub a few low reward missions to make high reward one easier
Can seem “unfair”
My skill keeps improving but I end up with the same result
Works best with strong and clear feedback

5. Save and Load systems There have been many variations
More onerous systems up the sense of risk and resulting accomplishment
More forgiving system encourage experiementation, creative play, and learning
This gets back to your game goals and target audience again

6. Content Player domain describes player’s interaction with the game
Game domain describes game systems that support those interractions
Content Domain describes the discrete assets that go into that experience
Story
Game narrative and/or backstory
Art
2D and 3D art assets
Audio
Audio assets

7. Game Design Courses at WPI
IMGD Design of Tabletop Strategy Games
IMGD 202X Digital Game Design
IMGD 403X Advanced Storytelling: Quest Logic and Level Design
(Slides courtesy of Dr. Mark Claypool)
IMGD 1001

8. Outline Gameplay (this deck) Level Design
Game Balance (Slides and exercises courtesy of Dr. Mark Claypool)
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9. Gameplay Player experiences during the interaction with game systems
Collective strategies to reach end points (score, goal)
Specific to game activities
“What the player does”
Includes
Utility - A measure of desire associated with an outcome
Payoffs - The utility value for a given outcome
Preference - The bias of players towards utility
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Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

10. Gameplay Example (1 of 2) Adventure game: Knight and Priest
During combat
Knight in front with sword
Priest in back casts spells (all spells cost the same)
E-bolts (do damage equal to sword)
Band-aids (heal equal to sword)
Fight a single opponent with sword
Which spell should Priest cast?
Against 1 big opponent with 6 arms?
Against 30 small opponents with weak attacks?
Can always decide which is better (not interesting!)
How can we fix this?
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Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

11. Gameplay Example (2 of 2) Now, suppose…
Band-aids still affect single target but e-bolts have an area affect
E-bolts do less damage, but armor doesn’t make a difference
Now, which spell should Priest cast?
Answer isn’t as easy. Interesting choices. Good gameplay.
“A game is a series of interesting choices.”
- Sid Meier (Pirates, Civilization…)
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

12. 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: Tank’s usually have “Taunt”
What for?
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?
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

13. Implementing Gameplay (2 of 2)
Should be series of interesting choices
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
Note, even Tetris and PacMan have strategy!
Game must display complexity
But doesn’t mean it must be complex!
Don’t make too many rules (“less is more”)
Ex: how many rules does chess have?
Emergence from interaction of rules/simple systems
Ex: In Populous, Priests convert, but not if already in combat. By design? Maybe, but non-intuitive result.
Remember the 3 body problem
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Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

14. The Dominant Strategy Problem
Articles with “10 killer tactics” or “ultimate build”
What are these doing?
Should never have an option that is so good, it is never worth doing anything else
Dominant strategy
Should never have an option not worth using
Dominated strategy
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Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

15. Near Dominance Worth looking for near dominance, too
Near-dominated – useful in only very narrow circumstance
Near-dominant – used most of the time
Ex: stun gun only useful against raptors, so only useful on raptor level (near dominated)
Do I want it used more often?
How much effort on this feature?
Should I put in lots of special effects?
Ex: flurry of blows most useful attack (near dominant) by Monk in D&D
Should we spend extra time for effects?
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Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

16. Avoid Trivial Choices Cavalry  Archers  Lancers Better (see right)
Transitive, not so interesting
Better (see right)
Cavalry fast, get to archers quickly with lances
Lancers’ spears hurt cavalry bad
Lancers slow, so archers wail on them from afar
What game does this look like?
rock-paper-scissors
 Intransitive, more interesting
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

17. Toolbox of Interesting Choices
Strategic versus Tactical
Supporting Investments
Compensating Factors
Impermanence
Shadow Costs
Synergies
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18. Strategic versus Tactical (1 of 2)
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 don’t build archers, can’t use tactically later
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

19. Strategic versus Tactical (2 of 2)
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
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Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

20. Supporting Investments
Often game has primary goal (ex: beat enemy) but also 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
Supporting primary goals are “one-removed”
Ex: improve weapons, build extra barracks
Supporting secondary 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)
Interesting since element of strategy
Payoff will depend upon what opponents do
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

21. Compensating Factors
Consider strategy game, all units are impeded by terrain
Ships can’t go on land, tanks can’t cross water, camel riders only in desert
Flying unit that can go anywhere  How to balance?
1) Make slow
2) Make weak, easily destroyed
3) Make low surveillance range (but could be unrealistic)
4) Make expensive
Common but uninteresting since doesn’t change tactical use!
Guideline is to ask what is best and worst about choices:
1) This move does most damage, but slowest
2) This move is fastest, but makes defenseless
3) This move best defense, but little damage
Most should be best in some way
What if ok in every way?  Versatile (next)
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

22. Versatility With versatility, a 4th choice:
4) This is neither best nor worst, but most versatile
Ex: beam can mine asteroids and shoot enemies
Versatility makes it good choice
Versatility, neither best nor worst
Good for beginners
Flexible, so often more powerful
(against unpredictable or expert opponent)
Speed makes units versatile
Common
Don’t make fast units best at something else
Versatile unit cheapest and most powerful
 not an interesting choice
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

23. Impermanence (1 of 2) Some things are permanent Others are not
Ex: you get a potion that raises max HP
Others are not
Ex: I got the “one ring” but you can grab it off me
Really, impermanence is another kind of compensating factor
i.e., impermanence can compensate for something being really good
a common and valuable technique
Can be used for interesting choices
Ex: choice of “medium armor for rest of level” or “invulnerable for 30 seconds”?
Advantage (or disadvantages) can be impermanent in number of ways.
How?
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

24. 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 don’t 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)
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

25. Shadow Costs (1 of 2)
In a game, you are continually presented with cost/benefit trade-offs
But not always directly
Ex: soldiers for gold, but need armory first for weapons and barracks for soldiers
Called shadow costs for supporting investments
And shadow costs can vary, adding subtlety
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

26. Shadow Costs (2 of 2)
Ex: Age of Mythology has wood and food. Food is inexhaustible, wood is finite
Direct cost for Charioteer: 60 wood, 40 food and 40 seconds
Shadow costs vary over game
Early on, food and wood expensive, spawn doesn’t matter (since make few)
Mid-game, much food and wood, spawn makes it harder to pump out new units
End-game, no wood, spawn is priceless
Vary environment and vary shadow costs
Ex: more/fewer trees to vary cost of wood
Use variability to add subtlety to game
Challenge for level designer
Expert players will appreciate
IMGD 1001
Based on Chapter 3, Game Architecture and Design, by Rollings and Morris

27. Synergies (1 of 2) Positive Feedback Negative Feedback
Synergies are interaction between different elements
of player’s strategies (note, terms may be different than Ch 2.1)
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 other’s way)
Diseconomies of Scope – (ex: mixed troops go only as fast as slowest)
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28. 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 grows long, game lasts a long time
Ex: Super NES NBA Jam – catch up setting as an equalizer
Be aware of both negative and positive feedback
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29. Learning curves “The 3 30s”
Comes from MMMOG design
What a player should accomplish in
The first 30 minutes
The first 30 hours
The first 30 days
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30. Learning Curves Skill Practice (Time) IMGD 1001
Stage 1
Stage 2
Stage 3
Stage 1 – Players learn lots, but 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.
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31. Difficulty Curves (1 of 2)
Practice (Time)
Difficulty
Stage 1
Stage 2
Easy
Medium
Hard
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…
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32. Difficulty Curves (2 of 2)
Practice (Time)
Difficulty
In practice, create a roller coaster, not a highway
Many RPG’s have monsters get tougher with level (Diablo)
But boring if that is all since will “feel” the same
“Treadmill effect”
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33. The Save Game Problem (1 of 3)
Designer talking about RPG
Designer: “I’ve got a great trap!” … platform goes down to room. Player thinks treasure but really flame throwers. Player is toast!
Tester: “What if player jumps off?”
D: (thinks it’s a loophole) … “Ok, teleport in then toast”
T: “What is the solution?”
D: “There isn’t one.” (surprised) “It’s a killer trap. It will be fun.”
T: “So, there’s no clue for player? Charred remains on platform or something?”
D: “No. That’s what the ‘Save’ feature is for.”
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Based on Chapter 5, Game Architecture and Design, by Rollings and Morris

34. The Save Game Problem (2 of 3)
Player needs to destroy 3 generators before leaving level (or next level, powerless ship doesn’t make sense)
Level designer puts up enemy spawner at exit:
Infinite enemies prevent exit
May think: "kill X enemies and I’m done!" (like Uncharted)
Only way to realize can’t leave is to die.
D: “After dying a few times, player will realize can’t leave and will finish objectives”
Lead: “At which point, s/he throws console at the wall!”
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35. The Save Game Problem (3 of 3)
Should be used only so players can go back to their Real Lives in between games
Or maybe to allow player to fully see folly of actions, for exploratory and dabbling
Don’t design game around need to save
Has become norm for many games, but too bad
Ex: murderous level can only get by trying all combat options
Beginner player should be able to reason and come up with answer
Challenges get tougher (more sophisticated reasoning) as player and game progress, so appeals to more advanced player
But not trial and error
IMGD 1001
Based on Chapter 5, Game Architecture and Design, by Rollings and Morris

36. Brainstorming Almost all good design starts with brainstorming
Brainstorming is iterative.
Starts broad
May return to it later for specific issues (Following slides and exercises courtesy of Dr. Mark Claypool)
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37. Outline
Motivation
Intro to brain storming
Exercises
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38. Motivation Building a game (or doing anything interesting) is tough!
That's why you are here? ;-)
Need to wrap your mind around the problem
Divide and conquer: split the problem into manageable parts
Iterate multiple times
Build team ownership
Ownership = commitment
This process is done at multiple levels, often with different people involved
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39. High-Level Process: Brainstorming
Start with a vague notion, and go from there
Move towards concreteness
Don't throw away ANYTHING!
There are no bad ideas
Write down every idea (on Post-it notes, a flip-chart, whiteboard, etc.)
Don't make judgments on quality at this time
MAIN IDEA:
Everyone should feel free to contribute
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40. High-Level Process: Prune the Tree
Now the group should have all ideas out there on Post-its, a whiteboard, etc.
First, remove anything obviously irrelevant, but be CAREFUL!
Now remove or combine redundant things
Group related things
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41. High-Level Process: Draw Relationships
Now draw charts and write descriptions for each of the remaining things
There are many solutions, so you will need to iterate
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42. High-Level Process: Validate the Design
Go through each object in detail, and verify that it meets all the requirements
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43. Some things to remember
This is not an ordered list
You can start anywhere, and go anywhere. Jump around
Answers to one question may add other questions or bring the answer to others
The one rule is to work from the most general to the most specific
There are no bad ideas, just scope limits due to time and budget.
In your case, 1 week to a treatment, 3 weeks to functional prototype
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44. Exercise 1: Do Now! Story, Player domain
Who is the target player?
What do they need or want?
What do they expect?
What kind of game is this?
We know it’s 2D, and that it will be played on PCs
What is the point of view?
What is the game genre?
What are the goals?
What is the fiction or narrative?
What if any backstory is there?
Don’t get too caught up in this: “Story is to game, as plot is to porno.” – J Carmack
What is the action vocabulary
What are the controls?
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45. Exercise 2: Content Story What Audio is needed? Text Art
What levels will tell this story?
What lore or backstory?
Text
What in game text needs to be written for levels?
What Audio is needed?
Sound effects?
Music?
Voice over?
Art
What sprites are needed?
What background art?
Special effects?
Explosions,
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46. What Next?
Go home and do the same thing in much more detail for your assignment
This should be fairly formal
Read through the examples
Don't write like you speak
Include appropriate visual support
Be thorough, ITERATE!
Software may help
E.g. checkout xmind,
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