Design properties

Low: outcome mostly fixed by prior state or chance (loot tables, saving throws). Medium: one meaningful choice among a small constrained set (push your luck: stop or continue). High: an open choice space where selection dominates outcome (worker placement, drafting).

Input = randomness resolved before the player decides (a dealt hand, dice rolled then allocated, a generated map). Output = randomness resolved after the decision (an attack roll, a loot drop). Code "both" only when the canonical form has both stages.

Solo: operates identically regardless of other players. Indirect: players affect each other only through shared state without targeting (blocking a worker space, depleting a market). Direct: targeted effects on a specific opponent. Cooperative: a shared goal is intrinsic to the mechanic (hidden roles is not cooperative, whatever its information coding; team-based is mixed). Mixed: canonical implementations routinely span two or more. Opponents controlled by the game system are not players: a mechanic whose canonical form pits one player against the system codes solo; code direct only when the canonical form targets another human player.

Low: one or two sentences, no exceptions. Medium: a paragraph with one to three sub-rules or timing exceptions; a single lookup table on its own is medium. High: several interacting tables, prerequisite graphs, or multiple interacting sub-rules.

Accelerates: snowballs or forces endings (clocks, end-game triggers a player can pull forward). Decelerates: lengthens turns or stalls progress (large-hand management, hit-point attrition). Variable: depends heavily on parameters (procedural generation, difficulty settings). Neutral: no systematic effect.

Scope is the mechanic’s own state. Perfect: all relevant state is public. Hidden: concealed from everyone (a shuffled draw order). Asymmetric: some players know what others do not (fog of war, a private hand). Mixed: both hidden and asymmetric components are intrinsic. State known only to the game system and to no player is hidden; state known to a human referee or game master but not to the other players is asymmetric.

Positive: success compounds (engine building, experience levels). Negative: success is penalised or trailing players are compensated (catch-up bonuses, handicap stones given to the weaker player). None: no systematic coupling. Mixed: the canonical form contains a built-in damper (deck dilution in deck-building).

Count within one turn of the player using the mechanic. Where the mechanic spans several players’ turns without resetting (an auction from lot to sale, a trick from lead to take), count that player’s decisions until it resets. Where play has no turns, count within one encounter in real-time play, or one move in a puzzle solved alone. A decision point is a moment where the rules give the player two or more legal options. Count decision points, not options: choosing among twenty spaces is one decision point. Count only choices the mechanic itself creates: choices made through other mechanics the game also has do not count, and a mechanic that is a constraint, a tally, or a frame with no choices of its own has zero. A referee’s or game master’s rulings on outcomes are adjudication, not decision points; where the mechanic is a menu of choices for the game master (GM moves), count those choices. Inputs that test execution (timing a jump, steadying an aim) are not decision points; count only choices between routes, targets, or tactics. Where the count varies, code the typical count in the canonical form. Code density without looking at agency; the two often disagree. Low: zero or one (victory points, initiative order, placing one stone in Hex, playing one card to a trick, the clue-giver’s turn in Codenames). Medium: two or three (set collection: which card to take and whether to cash in a set; cover systems: whether to move and to which cover). High: four or more (a deck-building turn of playing and buying cards, spending an action-point budget).