Rock, paper, scissors is a simple game, but it can provide inspiration for more involved game mechanics. The first interesting concept is that each possible move is equal to the others. No matter whether you choose rock, paper, or scissors, you have the same odds of winning assuming that your opponent picks randomly. Second, the game stresses the importance of simultaneous play. If you took turns when playing rather than simultaneously revealing your choices, the second player would always win.
In Dungeons & Dragons and many other role-playing games, actions are instead resolved by taking turns making choices, and on any given turn there is generally a pretty clear idea of what move is most optimal. What if these games adapted some of the concepts from rock, paper, scissors?
Aggressive, Defensive, or Adaptive
The basic idea of rock, paper, scissors could be overlaid right on top of D&D’s combat system. At the beginning of each round, each character would secretly choose a stance for the round: aggressive, defensive, or adaptive. Once the choices had been made, they get revealed and then the round of combat continues as normal. Aggressive characters gain a +2 bonus on attack rolls against those in adaptive stances because they push the attack before the target can react. Defensive characters gain a +2 bonus on attack rolls against those in aggressive stances because they take advantage of their opponent rushing to attack. Adaptive characters gain a +2 bonus on attack rolls against those in defensive stances because they take the time to analyze their opponent and find a weakness.
This is a relatively simple change that adds a small amount of blind choice to the system. I think it would be an interesting system to try with earlier versions of D&D that offer fewer options on attacks, but for 4e the idea of stances feels like it wouldn’t mesh well with the wide variety of power choices.
Simultaneous Power Choice
One way to add simultaneous choice to D&D 4e is to have all players and the DM choose their powers for the round at the beginning of each round rather than waiting for their individual turns. This adds an aspect of trying to predict your opponent’s actions rather than just reacting to their movements, but it also has a few complications. First, it makes winning initiative much more valuable. Not only does the winner act first, but they also have no uncertainty about the state of the battlefield when choosing their powers. In order to level out the playing field, I’d recommend rolling initiative each round after powers are picked. That way the initiative will give less advantage. A second problem is that there are cases where the originally selected powers won’t make sense. For instance, if a character is knocked prone or an ally moves into the cluster of enemies a character was planning to fireball. In those cases, I think it is reasonable to allow players to fall back to basic attacks and a standard move or stand up in addition to the move, minor, and standard actions they pick at the beginning of the round.
If you’re willing to make deeper changes or write a new game rather than just do a minor hack, I think the power selection concept would be expanded to make a game that places an emphasis on fighting styles. Characters would know one or more fighting styles that would each offer a small number of actions as well as potentially having some static bonuses or traits. For example, the Golden Dragon Technique could offer a sweeping kick, fire breath, and a resistance to fire. Each round, characters would secretly choose which style they were using in a round. Then on their turn they would be able to choose from a set of standard actions (move, basic attack, stand up, etc) and the options offered by their chosen style. Some styles could directly counter others allowing a more experienced character to adapt to an opponent’s choice or surprise them by pulling out an unexpected fighting style.
This feels like a very good match for games focused on martial artists, but I think it could also be applied to other character types. For example, for a spellcaster it could represent channeling a particular type of mana or pulling arcane reagents from a spell component pouch.