I found Black Mesa a few months after HL2 was released on the steam forum as very interesting topic came across my eyes
Pc gamer
Necroposter…
A thread in some random forum, if I remember correctly.
A Thread on Global Gameport, utilizing a link to the newest Black Mesa Source Trailer. Watched it, whispered “oh my god” several times, logged in to this website.
By asking what music someone was playing, And they said Black mesa theme…
And here I am.
That’s exactly how I found it!
Was looking up for HL2 mods over at moddb.com and this was mentioned, I heard of this mod way back (I even still have a Black Mesa Source song that I never noticed on the site again) but never got to actually joining the forum until only yesterday. 
I… can’t remember
It might have been Concerned, or wikipedia but i JUST. CAN’T- DRAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRRRRRGH
i found black mesa trying to find a legal way to get Half Life source for free i failed at that.
I found it looking for other mods a while ago. It’s been a long wait.
I think it was the Valve Developer wiki.
PC Gamer magazine once had that little thing on the bottom of a page with with a tiny blurb about Black Mesa. Next to the blurb was one of the teaser screenshots, and they had the website listed there. I looked it up and liked it.
I’m pretty sure I still have that magazine lying around somewhere…
Internet
_>
Anyone come here by way of noobish advertisements found on 1/5/20 dollar bills? =-)
My older brother, whom is also a big fan of Half-Life e-mailed it to me.
Was that your contribution to ‘advertise Black Mesa in the real world’, Catz?
Haha, I remember that. I think some of the pictures for proof are on the 404 now.
moddb
a MOTY a few years back I think.