My wargaming has followed, I think, a fairly orthodox path. As a boy, I started when by lining up my toy soldiers and rolling dice. I moved onto board games like Risk and Crossbows & Catapults. In my late childhood years, early teens I discovered Games Workshop and spent the next few years playing their games exclusively (back then, of course, they had a fair range of games.) I had stopped all tabletop gaming by the time I'd finished university, only to restart a couple years later and have been going strong ever since.
Obviously, tastes have changed over that period. Initially, I'd have thought it heresy not to play anything by GW, but that seems a bit ridiculous now! I'd also say that I play historical and sci-fi/fantasy games about equally; when I was at school, the idea of WW2 or ACW gaming would have bored me to tears!
My latest gaming habit is picking up sci-fi rulesets that aren't tied to any particular setting or range of figures, usually in pdf rather than print. Bizarrely, this is something I've never done before, the games I play having an associated setting and miniatures (Warmachine, Infinity, 40K etc.) The key to trying these was the fact we bought a wee tablet pc at Christmas, until then, I could never stomach reading a 50 page document on the pc. With the tablet, that's not an issue.
We've been trialling Gruntz at the club for the last wee while; great simple set of rules and lots of options for creating your own force. This week, another Scott from the club is running a game of Fireteam Andromeda. It looks a simpler game than Gruntz, but with an interesting C&C mechanic. We'll see how it turns out. Aside from these two, I've there are a couple other rulesets I've yet to read properly, the latest being Quadrant13 from the lardies.