Game Balance Jehee Lee Seoul National University

Game Balance Beauty in balance Game balance includes –Player/Player: Advantage in skill –Player/Gameplay: Learning curve matched by reward –Gameplay/Gameplay: Balance between features

Player/Player Balance Ex) Virtua Fighter (Sega, 1993) –Say, there is someone who play as Sarah Bryant and can beat every other character. –Does it mean unbalanced? –What if beginner as Sarah can beat expert playing Lion? –What if player can choose from a range of characters?

Player/Player Balance Victory by Skill and Judgment –There can be luck and gamble –Judging when to take risk can be part of fun Avoid luck dominating gameplay Symmetry is the fairest solution, but rarely the most interesting

Symmetry Legends of Water Margin –Two heroes square off for a duel –Stand watching each other poised in kung fu stance –Hours pass, days pass –Then a breeze stirs up dust –A speck goes in one hero’s eye –He blinks, frowns, and suddenly relaxes with a sigh –He bows to the other hero Masters/Experts know result of duel without having to fight

Symmetry No game should ever be decided by factor outside player’s control Symmetrical at level of significant factors Asymmetry is required for realism or aesthetics –Should be confined to minor factors –Should not sway outcome of game Perfect symmetry works fine with abstract game In real games, functional symmetry is more important –Units, levels, features

Intransitive Game Mechanics Zero-sum game –Player’s gain/loss is exactly balanced by losses/gains of other players. –Payoff matrix (see blackboard) –Player assigns probabilities to their respective actions –Ex: Rock-Scissor-Paper What if one player takes suboptimal strategy? –Ex: Rock (50%), Scissor (25%), Paper (25%)

Non-Zero-Sum Game Prisoner’s Dillema –Two suspects are arrested and separated. –If one testifies against the other and the other remains silent, the defector goes free and the silent accomplice receives the full 10-year sentence. –If both remain silent, both prisoners are sentenced to only six months in jail for a minor charge. –If each betrays the other, each receives a five-year sentence. –Each one is assured that the other would not know about the betrayal

Nash Equilbrium Two or more players reach equilibrium, if –each player knows the equilibrium strategies of the other players –no player has anything to gain by changing only his or her own strategy unilaterally –If each player has chosen a strategy and no player can benefit by changing his or her strategy while the other players keep theirs unchanged Not necessarily mean the best cumulative payoff

Player/Gameplay Balance Frequent negative reviews for new games –“Needless layers of complexity” –“Makes you perform every last chore yourself” –“Tasks are out of all proportion to onscreen rewards” –“Tiresome and frustrating” Balance –Not trivial, not too complex –Not too much labor, not too much automation

Case Study: Baldur’s Gate Begin with the player having to randomly generate scores in attributes –Strength, dexterity, intelligence between 3-18 You can take points away from some traits and add them to others You can REROLL to get a different set of values If you are patient enough, you can get all 18’s

Player/Gameplay Balance Balancing challenges against player’s improvement curve –Monsters get tougher with level –Widening options Three rules –Reward the player –Let the machine do the work –Make a game that you player with, not against

Reward the Player Player has to learn how to play –Mistakes are discouraging –Rewards for doing right offset discouragement Ex) Virtua Fighter –It takes a while to learn tricky combinations –Sarah flip over her opponent (eye candy) –Elbow strike to the kidney (payoff) Widening game experience –Ex) “Now with backflip, I can see new use for reverse punch” In general, better to reward player for doing something right than punish for something wrong

Let the Machine do the Work Question of the user interface Blur of boundary between chore and game feature –For years, RPGs used to boxed with graph papers, so you could draw a map as you explored dungeons If game option is no-brainer, consider AI talking care of it

Make a Game You Play with, Not Against Games can be spoiled by insisting the progress by trial-and-error Ex) crossbowman guarding the exit –Drink transparency portion. Sneak up. The guard sees and shoots you. Back to save. –Run up and attack. He is too fast. Back to save –Drop the bottle. He comes looking and shoots you. Back to save –Drink the portion and drop the empty portion. He walks by you for no reason. You finally escapes. Should succeed by skill and judgment, not trial and error

Case Study: The Save Game Problem A designer talking about dungeon RPG A: “I’ve got a great trap. The player steps on platform, it descends into a chamber expecting full of treasure. Then, flamethrowers go off and he is toasted.” B: “What if I jump off platform before it gets down” looking for a solution A: “we’ll have to make it a teleporter” seeing it a loophole B: “What is the solution?” A: “There isn’t one! It’s a killer trap” B: “There is no clue before you teleport. Is it a good idea?” A: “That’s what the Save feature is for.”

The Save Game Problem Save-Die-Reload cycle should not be a normal component of game experience Beginner player should be able to reason and come up with answer –Challenges get tougher as game progress, but –It should balance with the player’s learning curve

Gameplay/Gameplay Balance Challenges when balancing aspects of gameplay –Variety of interesting choices, rather than single dominant choice –Optimum choices depend on the choices other players make –How frequently different choices will be worth making Two levels of balancing: Component and Attribute

Component Balance Each choice reduced to a simple value relative to some other choice Ex) pirate game –Dreadnoughts > Galleons > Brigantines –All have identical functions –If Dreadnoughts 2x powerful, then Galleons should take ½ time to spawn –If Brigantines 2x speed, how can we weigh speed against power? –What if Galleons can attack flying units while the others cannot?

Attribute Balancing Involves not the relative values, but the way the choices interact –Assessing how important each attribute will be as opposed to other attributes –such as speed, firepower, upgradability, range, and so on) Use simple concepts to make first guess, then lots of play testing to fine tune Attribute balancing harder to get right than component balance

Combinatorial Explorsions How many attributes should you include to make interesting? –N factors leads to 2^n possible combinations “In Populous, should have lots of character types or only a half-dozen? I would be easier to understand the game experience with a few, very versatile units rather than many specific ones.” - Richard Leinfellner, Executive in Charge of Production at Bullfrog

Design Scalability Intransitive relationships are inflexible to alter –If we remove one component, some component may dominate Relatively easy to add components If you are going to scale, plan to scale up, not down