Dota 2
The successor to the mod/map that made the genre popular in the first place, Dota 2 is an up-to-date remake of the old Warcraft 3 mod which is still being played all over the place on various private servers. Coming from the people that brought us Steam and Half-Life, the game is especially impressive due to the huge amount of attention given to the game’s ability of functioning as an e-sport, with very good spectating capabilities, integrated commentary, the possibility of following a player’s mouseclicks to the point even.
The game’s as fresh as ever and I think you should play it just because of how good the last International was.