A recently finished game on chess.com was a real tactical melee for much of the game. Here is a position with the final tactical mistake:
White to move
Black has just moved Ncd4. On the face of it, the knights look like they are charging into white's position and positionally, black seems to be doing well. In reality this move just blew black's position and he is simply lost at this point. The whole game, including the winning continutation from this point can be seen at chess.com.