GTMU
    +-------
GHJ | PNRXGT
     -XHM
      ===
       RJX
      -NWP
       ===
        UHG
       -LWR
        ===
        GQXT
       -FHNQ
        ====
          JT

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: medium
missing: Y