When people search, they might type "zero ad," "oh ad," "0 ad," or even "zero a d." The numeral "0" itself can be tricky for search engines, as it might be interpreted differently or ignored, "A.D." (Anno Domini) is a historical abbreviation, but it's not a common gaming term. People might not immediately associate it with a video game.
A catchy, memorable name helps with word-of-mouth marketing. "0 A.D." isn't particularly catchy or easy to recommend quickly without further explanation
I think changing the name of this game to something better like, Ancient Empires, Stuff like that can improve the game significantly in the long run