Regarding missing encounters, I found out from the book that in the area of chapter 2 with the ferris wheel in Abkhazia (where you see a lone guy and a Gekko patrolling the area, before you meet your first box cyborg), ninja killing the two enemies results in NO RANK whereas if you get their attention and fight them properly, you get RANKED. Former means a blank space in the chapter results screen.
I guess this applies to other spots too throughout the game. Sometimes ninja killing just ain't beneficial to your score.
I guess this applies to other spots too throughout the game. Sometimes ninja killing just ain't beneficial to your score.