Marrik: For some reason, when I try to stealth kill people, it either makes me talk to them (if I use the Use key) or punch/hit them (if I left click). I seem to recall being able to necksnap anyone as long as I was crouched and behind them.

For instance, I remember being able to break the neck of the annoying ghoul guy in Santa Monica. Any suggestions?

alcaray: Are you seeing the stealth kill icon over your target? If not, you aren't getting close enough or lined up right. 'Use' key will work if you are doing everything right. Also, the target cannot have detected you or else it will not work (but you shouldn't get the stealth kill icon in that case).