OK. I only joined because this ran AcmlmBoard XD, so may I ask what it is first?

Why don't you go and ask something revolutionary? It's called... Google.

DotA is Defense of the Ancients, a multi-player battle arena! It started as a Warcraft 3 mod, and is now one of the most popular games in e-Sports (Valve hired the developer and created a full game on Source engine in classic Valve fashion).

DotA is the original, and it has spawned many copycats you may have heard of (League of Legends, Heroes of Newerth, Heroes of the Storm, Strife, Smite etc). It is a fantastic game and fully Free To Play (purchasable aesthetics but EVERYTHING gameplay related is 'unlocked' the first time you log in!)

The game is tons of fun and we've been playing it non-stop for years now, feel free to pull it down and come play a game with us.

Sounds alright and good description, binaryatrocity.
I thought no one would answer this actually but seems so.