I am managing Employee Engagement for a large print media organization and have concluded that employee engagement is not only about fun activities, although it always begins with that. Fun is the easiest way to open up people and then lead them to start treating their workplace as a fun zone to return to and work with an enthused mind, fully involved with high energy. You may call it an old wine (motivation) in a new bottle or the latest HR fad, but the purpose is to energize or charge employees to go beyond their "job role" and work exceeding the organization's expectations willingly. In doing so, they see their own associated growth in it.
I have found a few good articles that define the Employee Engagement theory, but the practical aspect is still in a nascent stage to emerge as tried and tested methods (see attachment). However, a broad framework helps in devising a customized Employee Engagement strategy and plan, which would differ from one company to another.
Best Regards,
Parul B. Kapoor