Condition Zero went down as a lead baloon. It had probably one of the worst timings ever to release a game. The game had such a rocky development it's incredible they even went out of their way to release it. It was supposed to release in 2002 , then in 2003 then in Q1 2004 and finally release one month before CS:Source. So you can expect no one played CZ when Source came out.
By all means Condition Zero is not bad, but it had a rushed development by the end of it since Valve changed the development team about 3 times because each of them had their own ideas, and in the end Turtle Rock Studios gave up and just retextured 1.6 and implemented a "Better" bot A.I.
One thing in my opinion this does right is the newer weapon models, which does actually look good.
By all means Condition Zero is not bad, but it had a rushed development by the end of it since Valve changed the development team about 3 times because each of them had their own ideas, and in the end Turtle Rock Studios gave up and just retextured 1.6 and implemented a "Better" bot A.I.
One thing in my opinion this does right is the newer weapon models, which does actually look good.