Protip: Shoot those red or blue !'s to stun an enemy for a short period of time. Strange white blobs come out of the top of their head too, for reasons I really cannot understand.

As for the question. I always assumed that a 'No Alert' game only counted if you went into 'Alert' mode. I may be wrong, but that just seems like a no brainer.

Also you really shouldn't be killing people unless it's really neccessary, it's what tranqs are there for.