The second option is to just update your old Warcraft 3 client.Here is a WC3 Reforged installation tutorial for it. Download the Blizzard client, login and install Warcraft 3 with your verified Warcraft 3 CD key.This is quite simple, you have two options: Read here how to get the game and what you need to know first. Warcraft 3 (Reforged) is the best game in the world! 😀
