I like to say an immersive sim is a game in which you can pick the lock on the back door, crawl through the rooftop vent, or bully the doorman.
Mark Ⴟ Ⓥ Delaney
"HEY DAVID", said the strawman, "WHAT ACTUALLY IS AN IMMERSIVE SIM??"
It's a game where you do at least one of:
1) crawl through air ducts
2) hide in the shadows
3) throw a guy at a guy