NTG
      +--------
MYQTG | JVGRZYN
       -LUNWX
        =====
         RZWWY
        -VYTRZ
         =====
         MLJRQN
        -MRGNPQ
         ======
          MPHGG

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
missing: H