A new Nintendo Direct was released by NCL today, revealing that a special classic level pack will be released for New Super Mario Bros. 2.  In celebration of gamers collecting over 300 billion coins in the game, the pack will be free until January 31st.  The pack will consist of rearranged levels from Mario Bros., Super Mario Bros., and Super Mario Bros. 3, and will feature new secrets hidden within the classic layouts.

At the moment, the level pack is only confirmed for Japan; hopefully a U.S. Nintendo Direct will appear shortly.

Source: Nintendo Direct