TGFR
      +---------
NGPTQ | UTGFQMNM
       -LYUJU
        =====
        NTWPUM
       -NNJRHY
        ======
         NRMFMN
        -NUJXWU
         ======
           QXWGM
          -JJYJM
           =====
           NTTXY

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard