An Aggressive Response (for black) against the closed sicilian? I am look for an aggressive response to the closed sicilian (1. e4 c5 2. Nc3 ...) in which black has strong attacking and tactical chances against white. Most of the variations I have seen result in black playing semi-positional plans on the queenside and center while white pummels black's king on the kingside.

Thank you in advance!
It's difficult to recommend an tactical line against the Closed Sicilian as White is attempting to avoid this sort play by keeping the center relatively closed/semi-open. I wouldn't characterize the play as Black playing purely positionally on the queenside and White "pummeling" black on the kingside - there are a variety of plans for both sides in the resulting middlegames. Black's expansion on one side of the board can be just as effective if not more so than White's attack on the king. An aggressive approach isn't limited to tactical play. I can recommend an approach that may make this concept more evident.

Against 1. e4 c5 2. Nc3, I have played 2...a6 in the past. Black's idea is quite simple - as he knows he's going to be playing on the queenside anyway, he decides to expand there before developing any of his kingside pieces. He usually follows up with moves like b5, Bb7, e6, and d5. This is certainly an aggressive reply to the Closed Sicilian, and can be defined as a positional one as well.