How long?

Started when it was first released when it wasn't popular and very buggy... all the beta editions.
1.3 was the first big-ish release then when 1.5 came out it became most popular.

lol i started like 2004 i think den i played like a year hardcore then stopped for ageess and went bac to source just recently..

about 2004ish been playing weekly ever since...

I was never really into counter strike so the first one i basicly played was source when i got half life 2

since 1st beta version