Elegance
Elegance is a term that can elicit groans from game designers and reviewers alike when it is invoked. It is thrown around often, and with many different meanings in discussions about mechanical systems. It is often conflated with the subjective quality of a game's systems or sometimes with their simplicity. This scattershot use of the term means that some people view it as an empty piece of praise or a relatively meaningless descriptor.
Obfuscation
Tension in game systems is created by the players be unaware of the outcome of the game. The moment they know how things are going to play out, the game loses almost all of its interest.
When designing a game system then, a designer needs to build in systems to obfuscate the potential outcomes from the player for as long as possible.
Affordances
Some objects or environments are better suited for certain uses than for others. A steep slope with stairs built into it is better suited to a human's climbing than one with a smooth surface, a round wheel is better suited to rolling than a square one, or a door with a protruding handle is better suited to being pulled than one with a flat metal plate. These objects' physical properties make them more convenient for people to perform these actions, and their properties can even imply these actions to an observer simply through their physical form.
Bartle's Taxonomy
If you playtest your game with twelve different people, you’ll get twelve different opinions. This kind of qualitative feedback can be invaluable, but sometimes you need to step back from the tangled web of personal opinion and get a broader view of how your game will be interacting with a player community overall. To do this, most designers (and other professionals analyzing large communities) use a categorization system to break the community down into different categories based on their motivations.
MDA Framework
This framework was originally taught as part of a workshop at the Game Developer’s Conference, and was later published in a paper in conjunction with researchers from Northwestern. It introduces a fundamental way of deconstructing game systems to give a shared vocabulary and methodology for people of all disciplines working with games.
Engagement Loops
Players constantly cycle through a loop as they play games, and each cycle starts with that player’s current mental model of the game. This mental model includes everything they know about the game and its systems—their understanding of the story, of the rules, of their final goal, of other players’ strategies etc.
The Magic Circle
The magic circle is a state of mind. It is a buy-in to the conceit of a game. It is a social contract between players mutually interested in having a shared experience. It is the bubble in which the normal rules and realities of the world are replaced by those of the game to everyone playing.