LQUG
      +---------
GGQFQ | WHUGLHFW
       -GGQFQ
        =====
        LGYPRH
       -LQXHRP
        ======
         LHTYLF
        -LFFLWT
         ======
          XQRNPW
         -XLYGXX
          ======
           XRXNU

base: 13
letters: FGHLNPQRTUWXY
difficulty: medium