XRPH
      +---------
XTPRP | GGLXXGYL
       -XTPRP
        =====
         WNLLG
        -NYPXR
         =====
          UWMQY
         -HHMPU
          =====
           VJURL
          -YMMGH
           =====
           XPVGR

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium
missing: Z