It started bubbling under my radar on a couple of the forums I visit, namely ttlg.com and yakyak.org.
In fact, my very first exposure to the game looks like it owes itself from a 2006 thread in TTLG's General Gaming forum.
People were talking about magma and rogue-likes, and linked to a story with attached pictures.
It wasn't Boatmurdered; it was one where a fireman came down a tunnel filled with water creating steam as he went, while the fortress's top archer slept through it all.
It all sounded utterly fantastic, with more attention to detail than I'd ever heard of from any game previously.
Then I tried to play it unaided, my brain went "Flurp?", and I gave up.
3 months later, after seeing it get mentioned more and more frequently, with more vigour every time, I decided that I was jolly well going to master this bally game.
I promptly proceeded to have fun drowning several forts in attempts to obsidianise imps, I flooded the world in one such escapade that resulted in my first experience of DF frame rate lag, yet I refused to gave up.
Like others, I clung to the wiki (and still do), until I got exposed to Tiny Pirate's tutorials which gave me the missing farming link needed to explode from barely self-sustaining fortresses where all food was bought from traders with crappy crafts, to continuously expanding fortresses with more food than they know what to do with.
And this isn't hyperbole; I really do think this is the best game in the world, hands down, no questions asked.