Arc can have two meanings:
- In storytelling, an arc is a particular plotline that moves a character from one state to another.
- In game design, an arc is a variant of a loop whose end state is not intended to significantly loop into repetitive actions. The theatrical killing blow in a boss fight, for example, is a type of arc.
For more on arcs, read Dan Cook's excellent Loops and Arcs article at Lost Garden.
