As a good rule of thumb - if someone can “win” in a fun activity, it's probably (at least partially) ludus. If not, it's probably paidia. read more
Additionally, Caillois suggests that games can be considered to lie at various points on an axis between free creativity and rule-bound complexity: Paidia refers to improvisation, and is discussed in The Anarchy of Paidia. Ludus refers to rules, and is discussed in The Complexity of Ludus. read more
A primary power of improvisation and joy, which I call paidia, is allied to the taste for gratuitous difficulty that i propose to call ludus, in order to encompass the various games to which, without exaggeration, a civilising quality can be attributed. read more