FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Benefits of Positive Feedback
Positive feedback can benefit your game in two ways:
■ Positive feedback discourages stalemate. A well-balanced PvP game should only rarely result in a stalemate, and PvE games should never end in stalemate. Positive feedback tends to bring games to an end because a player who takes a decided lead becomes unstoppable.
■ Positive feedback rewards success and provides that reward in a useful form rather than a purely cosmetic form, such as a higher score. Even though the perceived difficulty of challenges may increase, thus requiring the player to work harder nearer the end of the game, she still feels rewarded by a sense of power and growth at being able to do things she could not do at the beginning of the game. Because avatar growth is one of the key goals in role-playing games, the positive feedback cycle serves as the central design feature of the internal economy of computer role-playing games.
Although positive feedback generally benefits by helping bring a game to an appropriately timed end, especially in PvP games that involve direct conflict between the players, you must not allow positive feedback to operate so quickly that the game ends too soon or a player who falls behind never has any chance to catch up. Part of balancing your game will consist of adjusting your positive feedback cycle to prevent these problems.
Here are six different ways of controlling the rate of positive feedback:
■ Don't provide too much power as a reward for success. In chess, taking one of the opponent's pieces gives the player an added measure of power. In shogi (Japanese chess), the player can then add that piece to his own side, acquiring even more power. Introducing the piece directly would give the player too great an advantage; instead, it comes in as a weaker piece, which somewhat reduces the size of the reward. Similarly, in many war games, such as Warcraft, a player can destroy enemy factories, but he cannot capture them and use them to produce weapons for his own side. If he could do that, he would become unstoppable too quickly. (In real wars, armies often destroy their own production facilities and materiel to prevent them falling into enemy hands for precisely this reason.)
■ Introduce negative feedback. Negative feedback associates a cost with achievement to counteract the benefit—a negative reward, in other words. You may do this explicitly or allow it to happen automatically as a function of the gameplay. In Dungeon Keeper, the player can convert enemy creatures to fight for her own side, but once she does so, she has to provide food, money, and living space for them— explicit costs associated with adding them to her army. In the pool game eight ball, the greater the lead a player has on his opponent, the more difficult it becomes to
sink shots because he has fewer balls to target on the table, and his opponent has more balls left to get in the way. Pool doesn't include positive feedback to help the leader, so this negative feedback actually tends to keep games close.
■ Raise the absolute difficulty level of challenges as the player proceeds. This approach applies primarily to PvE games such as role-playing games. As the player gains experience points and treasure through successful combat, he obtains more and more power through positive feedback. In order to continue to offer him meaningful challenges, increase the strength and numbers of the enemy. Defeating stronger enemies yields larger rewards, so the cycle continues. Near the end of the game, he fights enemies hundreds of times more difficult to beat—in absolute terms— than those that he fought at the beginning, and this gives him a great sense of accomplishment. But because you have matched the absolute difficulty of the challenges to the power you provide, the perceived difficulty remains under control.
■ Allow collusion against the leader. In games with three or more players, you can write the rules in such a way that the other players can collaborate against the player in the lead. The collaborating forces may be sufficient to overcome the effects of positive feedback when the power of a single player might not be. Diplomacy encourages collusion—forming alliances is the main point of the game.
■ Define victory in terms unrelated to the feedback cycle. If you define the victory condition of your game explicitly in terms of player rewards, power, or success at achievements that make up parts of the positive feedback cycle, then positive feedback will hasten victory. But you can also define victory in other terms. Taking a piece in chess confers an advantage to whichever player took it, but the victory condition in chess requires the player to checkmate his opponent's king, not to take the most pieces. Although a player may achieve the victory condition more easily with more pieces, it can also be useful to sacrifice a piece for strategic reasons.
■ Use the effects of chance to reduce the size of the player's rewards. Roleplaying games do this to some degree by randomly varying the amount of loot that enemies yield to the player when they are defeated. By occasionally giving players a lower reward for their achievements, you slow down positive feedback.
