Hi, thought I’d share this here but on the downloads section of the Blizzard website there is still a way to play Warcraft 3 on the classic client along with classic battle net via the Public Test Realm version of the game found at the bottom of the download page in the Classic Games section.
Download Battle.net for Windows and Mac | Battle.net.
You either need to own Reforged or have a Reign of Chaos CD Key in order to play it though but most if not all classic users should still have their CD Key in order to play it.
This is the classic version of the game (RoC and TFT) and as such is only about 3GB.