GFG
       +---------
XHCGTU | HUFXXGXT
        -XHCGTU
         ======
         GGXGCGX
        -GUTHXGU
         =======
           HXXUXT
          -XHCGTU
           ======
           GTXHCT

base: 7
letters: CFGHTUX
difficulty: intermediate