Like New - Opened box, but never was able to complete the puzzle.

I am assuming all pieces are accounted for, but since the puzzle was never completed I can not state that sure.  You will be taking a chance.  However, I take care every puzzle we own.  I keep and maintain them in great condition in the box.  Hopefully, all pieces are in there.  

It's a super hard puzzle for me.

This is definitely a collector's puzzle.  In great condition.  

DC Comics The Dark Knight & Joker 1000 Piece Jigsaw Puzzle 20"x27" Keith Ledger