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Nautical Flag Cipher

Before Wi-Fi, ships sent messages by hoisting flags from the International Code of Signals (ICS). Type a message to see it as a flag hoist, or try to decode a security tip run up the halyard. Hover or tab to any flag for its letter and its single-flag meaning.

How to play: Encode turns a message into flags. Decode shows a hoist and you type it back. Hints cost two points.

Note: a real ship carries one of each flag, so repeated letters are signaled with substitute (repeater) pennants. This hoist draws every letter literally to keep it readable.

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