Counter Strike
Which one?
CS1.6 is fairly popular albeit very hard to master.
CS Source is popular and its got a lot of casual servers(IE Anything that doesn't consist of Scrim , PUG's or PUB's.)
CS Global Offensive is probably as popular as Source and its got a matchmaking system if you want to go competitive alongside the ability to join casual servers with lots of gamemodes.
1.6 and Source are fairly different games. You might want to look into both before you try one. Though to my knowledge yes, Source has a much larger number of fun derivative games like Jail, Zmod, Zescape, GunGame, and such. It can take some work to find a really good pub rotation server that isn't just constant dust2 or office, but I've found a few that were really amazing and that I stuck with for years.
GO is the funny-smelling younger brother of the two. It's shiner, but the buy menu is a pain in the ass and IIRC it also has a lower population these days. You can still find games easily enough because MM, but I would definitely peg it as lower-quality than Source or 1.6.
I just found it puzzling that someone would come to a niche gaming forum to inquire about what games are currently popular. Like going to Le Meurisse and asking where the best McDonalds is located. There are a multitude of ways to get that info through steam. Like with a single click.
DF may be a niche game, but this (sub-)forum discusses popular mainstream games quite frequently. I mean, Dota 2 alone has a 250ish page thread here.
There may be a more appropriate places to ask this sort of thing, but that doesn't mean this forum is actually an inappropriate place to ask. Certainly not to the point of mocking the thread/OP.
This. Especially on the lower boards; a lot of us haven't played DF for years, and most of us are avid gamers of one stripe or another. Really, there's no reason to be a jerk to the guy, especially considering that this thread completely fits the topic and tone of this sub-board. We've got enough problems with perceptions of elitism on our part without people filling the role perfectly. It's not only possible but normal to like things that are both "niche" and "mainstream", though I dislike calling thing either because normative implications blah blah blah.