RTP
      +--------
TTVHW | YHWPGZX
       -JLLMR
        =====
        WYQPZZ
       -WJVXHT
        ======
         WGMURX
        -WTZQMP
         ======
          XGGWU

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: challenging
attributes: conditional, excellent
missing: N