Warcraft 3 is a real-time strategy game in which you stand on the side of the races of the orcs, the humans, the night elves, or the undead. In the end like most strat games: build up, attack, and either get your butt handed, or hand it out yourself.
Blizzard is still offering WC3 for sale.
Despite its age, the game already has a copy protection (SecuROM 2). With CloneCD you can create a usable image. However, this is more of an academic nature, because the copy protection doesn't prevent you from installing it, but only hits you when playing an unpatched game. Installing and patching is enough if you install the last patch 1.26a. After that the game has no more CD query and can use all resolutions of the graphics card. The Battle. Net version is a different matter.
If you want to host games from the CD version yourself, you should open port 6112 (TCP).