I was wondering if in the novel we knew about some deaths occurring before Kayaba announcement. I remember that in the anime, Kirito plays a bit with Cline before realizing that the log off option has disappeared. Then all the people are summoned to the city and learn about the fact that if they die in the game, they also die in real life.
I don't remember any players dying before the announcement in the anime, except for those who are not waking up and their relative pulling off their NerveGear thus causing death, but maybe in the light novel, some guys died without even knowing it just while being defeated by a mob (which seems awful for me).
Do we know about some players dying before that while thinking they are still in a normal game?