And TBH, those are the only two criteria I look for. I think audience agency, multi-sensory activation, etc, are all plus ups. But in my mind, those are bonus features that enhance the experience, but aren't necessary at the distillation of what makes an experience or production immersive or nah.

And for 2. It can't be the authentic thing. I talk frequently about going to an advertised "immersive beer tasting" to find it was just an actual tasting at a brewery.
To be capital I immersive, it should be a depiction, an experience representational of the reality being described. Otherwise, why?

For 1, I know it's not realistic that EVERYTHING the audience sees is going to be within the narrative world. That gets expensive as hell in physical works.
But the goal is that the audience believes the environment in which they inhabit is the same as exists in the narrative they are experiencing.

A quote from Garry Newman [Garry's Mod] I think about often

UPDATE: “Act of terror” leaves several injured on Boulder’s Pearl Street Mall

Officers were called to an area near the intersection of 13th and Pearl streets about 2 p.m. Sunday. Federal and local authorities are investigating.

coloradosun.com/2025/06/01/b...

I routinely break Dunbar’s number — it’s part of my charm — but this is absurd