Plenty of good stuff in here already, but here are my two cents, from the perspective of someone who's not talented at games and is too lazy to 'train' properly, but nevertheless got heavily into Warsow/Quake/Reflex, and became an enthusiastic mid-tier dueler. (It probably seems rather self-obsessed, but the reason for talking about myself so much is that mine is the only path to loving the game that I can talk about with any real understanding.)
- early on, what got me into Quake 3 was how fun it was to play badly, either on a small LAN with friends (and bots) or alone against bots. I didn't know strafejumping existed, paid no attention to armours, probably didn't even realise the powerups were predictably timed, but just had a blast walking around shooting. Obviously part of that was my young age and the relative novelty of any FPS game to me at the time, let alone one that I could play against my friends, but it also had a lot to do with the game itself. I'm not a game designer or a genius so I'm not sure exactly why Q3 grabbed me in that way, but there was something to it that didn't depend on any of the depth that I discovered later on. One thing that I know was important, and which I've mentioned before, was the structured single-player component. It was very simple, but it gave me some specific challenges to take on and a way to measure my progress from complete noob to slightly less of a noob.
- at some point I very briefly tried CPM, but found it confusing and didn't give it a serious go.
- much later I discovered Warsow, which is where I really got into the meat of the Quake experience. (But I think I was predisposed to give it a go, and to enjoy it, because of my positive feelings about Q3.) The first thing that grabbed me was the movement: I could see what was possible from watching other players in-game and on Youtube, and got a little taste of it myself thanks to Warsow's newb-friendly (but still incredibly hard to master) movement system. For a while I only really played DA (the A1v1 equivalent), and just had a great time rocketjumping off walls and gradually learning to strafejump. Duel wasn't fun for quite a while, and if it were the only active mode I think I probably would have given up. But eventually, having played the occasional duel in between games of DA and CA, I got a feel for the subtleties and realised how enjoyable the tactical struggle could be when combined with the movement & shooting I already loved.
From there I went to QL, CPM and Reflex, but discovering that I enjoyed Warsow duel was the point at which I really got hooked. Having an active community was important, but it didn't need to be huge -- just a few friendly people to help me get started, one or two regular duel partners at around my level, and some better players to look up to and measure my progress against.
I'm not sure exactly what the lesson is from my experience -- perhaps something about the elements that attracted me as a newbie being quite different from, but not incompatible with, those that kept me interested -- but I thought this might at least provide a counter-example to the suggestion that games like Reflex aren't 'fun' and are only really suited to people who are motivated to put in hours of practice and take the game quite seriously. Of course I have some competitive spirit, but I've only really learned by playing, and played because I enjoyed it. I never got very good, but good enough to appreciate some of the subtleties of the game and to enjoy competing against some decent players. (And, perhaps most importantly in the context of this thread, to play a lot and become reasonably active within the community.)
edit: one thing that I forgot to mention is that immediately before discovering Warsow, I'd been pretty heavily into TF2, but eventually got fed up with some of the bullshit surrounding it (this was around the time it transitioned from being a game people played because it was intrinsically fun to a glorified skinner box), as well as the feeling that the gameplay itself was fairly restrictive. Two of the great things about Warsow (and other Quakelikes) was their purity (no unlocks -- which still pretty much holds for Reflex since they're all purely cosmetic -- or other shortcuts to addiction, no critical hits, no attempt to hide skill disparities, and so on) & the freedom (of movement, of play style, to exploit their nuances rather than having everything locked down with speed caps and invisible walls, etc.) that they allowed.