RTWG
      +---------
JWXHQ | MJRGJWLQ
       -JWXHQ
        =====
         LTTHW
        -XHLYP
         =====
          XUFWL
         -QWRWN
          =====
          JMQPNQ
         -JJNLPN
          ======
           RJMNM

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: medium