For the most part, I found ns2 fairly relaxed. It was nice not to be doing a moba..
NS2 is fairly relaxed (well, as relaxed as it can be with hungry aliens jumping from ceilings and eating your face). The people are usually pretty nice, and there's no that much individual pressure to do well, mostly because it's much harder to keep track of what each person is even doing anyway. Even if you die, you respawn almost instantly, so it's very non-stress. Of all the team-based FPS games out there, it's probably the best for casual players (that I've seen) because you've literally got a person telling you where to go and what to do, and teamwork is so important that your entire team is always communicating.
It's actually really cool, the environment is so well-done that when I hear my teammates talking over the radio, sometimes I pretend I'm in a Sci-Fi movie and the suspension of disbelief is not that hard. "WE'RE LOSING SKYLIGHTS GUYS, WE NEED EVERYONE HERE NOW." "WE HAVE TO KILL THEIR HIVE BEFORE THEY TAKE OVER THE ENTIRE MAP." "WE NEED SUPPORT IN GRAVITY CONTROL, WE'RE GETTING OVERRUN."
It's really awesome, especially because you usually have the Commander talking, and maybe 1 or 2 Lieutenants in the field. Until you hear a squeaky 13 year old's voice, and then you're like, "Damn".