I was introduced by my best friend back in the day. Cant remember how long ago exactly but I think it was 2 updates before condition zero (1.3??) was absolutrly hooked. Then I bought a copy of the game along with HL, Oppose forces, and Blue shift.
Dabbled here and there as I was the only one of my friends who enjoyed cool games other than goldeneye. I gave my buddy my copy of the game, as I was bored of it and he registered the SID when CZ and STEAM came out. Then He got me back into it and wouldn't give me back my game with the old SID (Piece of shit!) So we stopped being friends soon after and I started back up when I got game of the year HL2 and CS:S.
That same friend introduced me to TD randomly about 2 years ago. He got banned multiple times for being a PITA (his name was Flying Horse / African God if you remember) and I stayed ever since.