In order to describe how a game is played over time, one must take into account the range of effects the players actions have on the characters, enemies, and the environment. Previously on Critical-Gaming, we've described game mechanics as being concrete versus abstract, and existing in one of three levels: primary, secondary, and tertiary. Primary mechanics are a limited set of mechanics that make up the core of the player's interactivity and the core feeling/action of a game. Secondary mechanics are typically designed to support the primary mechanic by giving it more variation and rounding out the feel of a game. Tertiary mechanics are actions that can only be executed in limited contextual situations that depend on an outside source (ex. an enemy).
In real life, every action has an equal and opposite reaction. I translate this as every action is a part of a push-pull system. Because actions are so intricately and intimately interconnected, the effects of a single action can cause a domino effect of cascading dynamic reactions. Such is the richness of life. Like in life, game mechanics that exist within a game world that are part of a push-pull system yield richer, more versatile, deeper gameplay experiences. This is the essence of interplay.
Interplay is the back and forth encouragement of player mechanics between any two elements in a game. Put simply, interplay is where actions and elements in a game aren't means to an end, but fluid opportunities that invite the player to play around with the changing situation.
The easiest way to think of interplay is offensively/defensively or in counters. Consider two elements of a hypothetical action/fighting game. The first element is the player's character, and the second is an enemy. If an enemy can attack you, does this attack/enemy have a way to be countered? What happens when you counter the enemie's move? Does the enemy die, does it reset itself, or does the situation change? If the situation changes, is the enemy still a threat? If so, can you counter the new threat? And the cycle repeats.
Once you have run out of counters between the two elements you're examining, it's easy to map out which mechanics were used at each level, what kind of mechanics were used, and what additional elements were involved in the situation. Only with all of this information can the interplay of two elements be accurately described. The greater the level of interplay involving higher (more primary) mechanics and level elements, the deeper and more dynamic a game is.
Now for some examples.
Donkey Kong Jungle Beat
All the bosses in this game are designed with a well balanced amount of interplay that allows the player to constantly flow with the action instead of waiting around for weak spots to reveal themselves.
Even in this relatively simple boss Torch Tusk, players can utilize throwing explosive pineapples offensively to counter the boss attacks of fireball projectiles and lasers. When Torch Tusk is taking in air to shoot the fireballs, players can throw a pineapple so that it gets jammed inside of its tusk. Players can also stop the laser by hitting Torch Tusk with a pineapple while its discharging the beam. At the same time, the boss can counter the player's only offensive option by intercepting an incoming pineapple, letting the small flame walls detonate the planted pineapples, or blasting them with the laser beam.
This kind of offensive interplay keeps the momentum high because the player always has something they can do to gain an advantage. Because the player's only offensive option is using the pineapples that are located at the exposed top and bottom platforms, the player is more likely to move around the field platforming in a variety of ways.
Super Mario Galaxy
In this battle with the boss Bouldergeist, Mario can't attack the boss directly. In order to do damage, Mario must blast away the rocky exterior using Bomb Boos. Once the weak spot is revealed, more Bomb Boo will finish Bouldergeist off.
Bouldergeist attacks Mario with punches, shockwave rock walls, hand slams, and projectiles rocks (some of which contain Bomb Boos). Mario can avoid all of these attacks by maneuvering, but he can only directly counter the projectile rocks with his spin attack or by shooting star bits at them. From this point, the rocks that contain Bomb Boo's are the Bouldergeist's second level counter. Even if Mario avoids the rocks, the Bomb Boos will then seek out Mario and explode on contact. These Boos, like most Boos, cannot be hurt with normal jumps. With these guys, Mario must counter them with a spin attack. This is the 3rd level of interplay.
By spin attacking a Bomb Boo, Mario can swing the ghosts around by their tongue for an explosive attack. Attacking in this way is the only way for Mario to damage Bouldergeist's main body to expose his weak spot. To counter Mario closing in for the attack, Bouldergeist's attacks take on a secondary function. The hands and rock walls in this case also function as shields protecting the main body. Now, when jumping may not have been necessary to dodge the incoming attacks, it may indeed be necessary to avoid hitting Bouldergeist's defensive moves. This is the fourth level of interplay.
The final level comes from an ability built into the Bomb Boos themselves. As Mario swings them around by their tongues, the Bomb Boos will slowly retract their tongues bringing their explosive bodies closer and closer to Mario. This final defensive counter dynamically shortens the swinging radius around Mario. The Boss knows this, and when he has nothing else to defend himself, his final move is simply backing up to increase the distance and the swinging time between him and Mario. This fifth level of interplay creates an exciting battle of spacing and timing. Also, the length of the Boo's tongues make a perfect timer that fits snugly within the tenet "form fits function."
Interplay doesn't have to reach any particular level in order to be interesting, useful, and well designed/integrated with the rest of the game. Just having multiple one step interplay elements can build exciting and rich gameplay experiences.
Viewtiful Joe's enemies and bosses are action packed because of the high amount of interplay in their design. Though the level of interplay doesn't typically go past 2, the mechanics involved in the interplay are all highly interconnected. A single attack from a boss or enemy has at least one obvious counter. At any time, players can use their special fx powers to speed up time, slow it down, or zoom in the camera to adjust the difficulty of executing the counter in real time. In other words, if an attack is too fast for a player, they can simply slow down time to make things easier. But as the enemies and attacks begin to layer together, things get more complicated. All the while, the energy that Joe needs to stay powered up drains away. When Joe is all out of energy, he not only losses his super powers like his fx powers and his double jump, but he takes more damage as an "ordinary joe." During the most exciting battles, players are fully engaged in the push-pull inter-gameplay.
Some examples of interplay can branch from a single point. Take Squirtle's withdraw attack from Super Smash Brothers Brawl. With this move, Squirtle tucks himself into his shell and slides forward. While inside his shell, Squirtle cannot take damage. Also, the moving shell can hit objects and opponents for a weak attack. With these two properties, this move could have been unbalanced because of its offensive and defensive abilities. Fortunately, counters were built into this move that comply with form fits function. Opponents can strike the shell to counter its trajectory. Though Squirtle won't take damage, he will slide in the direction of the attack according to the strength of the attack used. So it's possible to smash the shell off the stage so that Squirtle has to extend himself just to recover back to the stage. Opponents can also counter the move by jumping on top of the shell Super Mario style. When this happens, Squirtle is flipped on his back helpless as he struggles to turn himself back over. If all the moves, especially the stronger ones, had this much interplay, Brawl would be a much better game.
If an individual game action or element is analogous to a musical note, then interplay is how the range and variety of notes are created in a videogame. Long held notes, short notes, syncopation, grace notes, and runs up and down a scale are analogous to game mechanics like charging a bast in Megaman, small jumps in Mario Bros., countering in Ninja Gaiden, angling an up-B recovery move in Smash Brothers, or riding down an icy mount in Donkey Kong Jungle Beat. Interplay is how the music of a game can move beyond simply recognizing the situations to use a mechanic, executing the mechanic, and moving on.
Tomorrow, I'll go into detail about the interplay in Super Mario Bros. Bricks. Goomba. Koopa... the genius of these seemingly simple elements will be revealed. Stay tuned.