[Ref: ZWPU] © Alan Stillson and Frank Longo.
- Place letters into the grid such that every row, column, and 2x2 block has letters (in any order) that form a common word.
- Each letter is only used once, and no letter is repeated in the rows/cols/blocks.
- Letters allowed: C O L U M B U S.
Hint: Column 4's missing letter is L.
Back to the puzzles...