Which term describes features that motivate audience participation on a site?

The term that best describes features that motivate audience participation on a site is "Game Dynamics." This concept refers to the various elements and structures that engage users, encourage interactions, and push them towards active participation. Game dynamics can include challenges, rewards, and social interactions, which all create an engaging environment that draws users in and keeps them involved.

While game mechanisms often refer to the specific rules and paths that guide behavior and interactions within a game-like system, they serve as a foundation to create dynamics that foster participation. Visual style pertains to the aesthetic elements of a site, which, while important, do not directly drive audience engagement. Social tone reflects the attitude and personality conveyed through communication but does not inherently engage users as game dynamics do.