????????
      +---------
GJNRQ | QUQJNLPR
       -WVUNZ
        =====
        VJGVWL
       -VNQUYY
        ======
         VNJHVP
        -VLYGXJ
         ======
          GRLLNR
         -GYRJTW
          ======
          ??????

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
attributes: long
missing: M