Never heard of immersion journalism until last Sunday. Some journalist were discussing it on a C-SPAN book TV program. Although, I may never have heard the terms before, unbeknownst to me, I had previously read an immersion journal article. It was an amazing New York Times article called 'Snow Fall: The Avalanche at Tunnel Creek' by John Branch. Some of you have viewed it already. I say viewed because with immersion journalism it's more than reading, it is a 3D interactive non-fiction experience. Immersion journalism differs from gaming formats. For one thing it is long form journalism. Visual enhancements are integrated into the reporting.
There is a lot of hand-ringing within the newspaper and magazine business regarding loss of advertising revenues, and problems with profitable mobile advertising. Well, stop the moaning an jump onto and put your readers into long form immersion journalism.
I guess I should warn you that the term is not exclusive. Some reporters use this term to describe a reporting style where you immerse yourself in the story sans the interactive features. Anthropologists and sociologists have done this for years it's called participant observation. It's more of a longitudinal reporting. What we are talking about here is an evolution in newspaper and magazine reporting. It may or may not be longitudinal but in will always be integrated with interactive features.
If you want to know more about immersion journalism Wikipedia has a comprehensive description.