I sometimes look to traditional games for mechanical inspiration. One of the ones I think of most often is chess. Clocking in at over 1,000 years of play around the world, chess has had a lot of iteration time. I'm not an expert on chess strategy and I'm not a particularly good player, but I know chess well enough to take some simple lessons away from it. Two that I often rely on are lessons of obvious value and orthogonally equivalent value. These two lessons can be summarized by examing three chess pieces: the queen, the knight, and the bishop.​

[...] The queen is typically the most powerful piece in chess (though not the most valuable; that role is reserved for the king). The queen's movement capabilities combine the lateral movement of the rook with the diagonal movement of the bishop. Even if you are learning chess for the first time, the fact that the queen combines the movement of two other pieces makes her relative power clear. A rook's ability to perform a castle, the knight's excellence at creating forks, and a the pawn's ability to capture an enemy pawn en passant are all capabilities that take a while for players to appreciate, but not the queen's movement. The queen's value is obvious.​

Gameplay consists of players making (more-or-less) informed decisions about what they need to do to overcome an obstacle. It is not enough for the obstacle to be clearly defined and communicated to players. They also need to have a clear understanding of what tools are at their disposal to solve the problem. In chess, the player's primary tools are his or her pieces. Though circumstances determine the value of pieces on any given move, no one needs to advocate the fundamental value of the queen in chess.​

[...] Chess has various informal ranking systems for the relative value of pieces. The rankings are not used for scoring, but they are used to give players a rough idea of the strategic (not tactical) value of those pieces. In the most commonly used system, pawns have a value of 1, rooks have a value of 5, and queens have a value of 9. Knights and bishops are both rated at 3. Bishops move diagonally, always staying on their starting color, and knights are the "funny moving" pieces of chess, hopping two squares horizontally or vertically and one square vertically or horizontally, passing over other pieces along the way. Though their tactical applications in any given circumstance are completely dissimilar, the common ranking systems give them equal (or close to equal) strategic value in chess.​

[...] When we design tools for the player to use -- abilities, gear, options, upgrades -- options with ostensibly orthogonally equivalent value create interesting choices for the player. They also lend themselves to increased clarify of purpose. The more tools overlap in function, the less obvious it is to players why a given tool exists. The less tools overlap in function, the more those tools seem suited to a specific circumstance.​

While these are high-level design concepts, creating choices with obvious, easily differentiated values can make the low-level details much easier to execute and build upon. When a player is presented with strategic or tactical choices, he or she is always fundamentally asking the question, "Why do I want to make this choice instead of any of the others?" As designers, we want to communicate the answers to their questions as elegantly as possible. Ideally, the design of the player's tools and the game's content should be self-advocating, allowing players to reverse-engineer our intent and their range of choices without a word of explanation.​

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