I think I just searched the internet one day for some graphical improvement mods for Half-Life and I found Black Mesa. Or maybe I heard about it through Steam. Not sure. I’m relatively new, compared to some here, but I just realized I’ve actually been here quite a while.
I don’t remember anymore but I bet I discovered it while browsing through some hardcore porn.
The German gaming magazine GameStar once had a video special about the most expected games of 2009, which also included the BM trailer.
I, too, have a clouded memory of how and when I heared from this. The closest call would be, me searching for a graphical update mod for HL years after HL:S was just a tech demo for porting, not the actual thing (When I read the contents of the orange box I was like, ‘yeah! HL in HD’ and then I was ‘CRAP!’). Then on Youtube I found the 2009 release trailer.
Tuned in since…
IIRC I found this mod whilst searching for HL2 mods on ModDB, it was at the beginning of 2010 when everybody on the forums were still pissed that Black Mesa had missed the 2009 release date. 
I found BMS after I first played Half-Life 1, I watched the trailer in 2009 
I found the mod few days after beating Half Life and Half Life 2 on a marathon, I found out about in the teaser, which was so popular, and the leak in 2009
When I first started playing Half-Life, a friend told me about this mod.
As a matter of fact, I’ll be completely honest here. I didn’t play Half Life before Portal. Then I heard of this place at the end called “Black Mesa”. So, I googled that and found this mod. After finding out that this mod was a recreation, I decided to get Half Life. And this is my life story… I played HL 2 before Half Life T.T
What leak?
I found it looking for HL2 mods… then my life was temporarily put on hold while i silently wait…
Edit: Now that I think about it I think I found out about it just after the leak sometime.
I was in a page talking something about Half life 3 and there was a link that said: “until the release of HL3: www.blackmesasource.com” and here we are
Ah yeah, that Hot Mario Bros. Mario Kart DS commercial… those were the days. 
I believe a number of outdated assets (maps, weapons, etc.) were leaked around that time. If you want to see, there are a few YouTube videos showcasing “alpha gameplay” with them.
Pfft, no idea. Definitely after I completed all the Half-Life games, which was in '08. I probably googled HL1 graphics mods.
That was in 2006 not 2009.
I think you’re right, but I only knew of that leak in 2009, I kinda had gotten off the mod by 2008, so I thought that it had been in 2009, sorry for being a shameless noob…
I’m pretty sure I discovered this site when I was pissed off that all Half-Life: Source added was better water, physics, ragdolls, and better explosions. I think I did a search and found this mod. Looking back, I don’t know why I expected Valve to do anything more than that.
Well, I…
…
I DONT REMEMBER !!
I’m totally serious.
Well this is awkward:|
^i had to think pretty hard too. Its been a while 
@keresh I thought the leak was later than that. I’m terrible with dates. My mistake.
Found the trailer by accident on YouTube back in 2009, then after searching all over the forums for a month i forgot about it. Then in early 2011 i discovered it again and have silently been reading the forums everyday since.