Hello and welcome to DOTA 2! Sequel to Defense of the Ancients: All-Stars, DOTA 2 has a prime lineage of moba awesomeness.
"What is DOTA?", you ask, eyes filled with tentative wonder. Well...
DOTA is a fast paced strategy action game....thing. You kill dudes, get gold, gain exp, all so you can kill more dudes with the eventual goal of killing your opponents Ancient and winning the game.
Here's a guide so I don't have to regurgitate shit and make this op a billion pages long:
Probably the best way to lose 40 minute chunks of your life while being completely focused on a game where 10 players throw racial slurs at each-other.
Any flaming with regards to dota vs hon vs LoL will be infracted on sight.
I also have it, and play it occasionally. You have to fix something there, DOTA isn't fast paced, at least in comparison to HoN(which is still a better game in my opinion).