Morse code puzzle

How to play the Intercept

Somewhere in the static, someone is sending a message. You have a valve radio set with two big brass knobs. Turn FREQ to find the station on the band: every carrier shows as a spike, and the tallest is the one you want. Then turn PHASE until the dashed reference trace lines up with the solid signal trace. As you close in, the whistle slides down to a steady note, the hiss drops away and the meter climbs. At 90 percent the signal locks by itself and the LOCKED lamp lights.

Then you decode. The message plays and also appears as a transcript, so you can work it out with the sound off. Spell the one-word answer on the brass letter wheels under the paper tape, or type it. The word tries itself the moment it is right.

The three kinds of message

• Morse. International Morse code, one cluster of dots and dashes per letter. A code card is one tap away.
• Reversed. The same Morse, sent with the last letter first. The source line tells you the set sends its message backwards.
• Tones. Each letter is two tones: row, then column, on a five by five grid. Tone 1 is the lowest note and 5 the highest, and I and J share a square.

Tips for Morse code puzzles

• Tune coarse first. Tap the band strip near the tallest spike, then turn FREQ for the fine work. FREQ alone takes the meter to about 30 percent.
• Beware decoys. Some days the band holds weaker spikes that look promising. The station is always the tallest.
• Learn the short letters. E is one dot, T is one dash, and A, I, M, N are two signs each. Recognise those and long messages shrink.
• Write the clusters down in order, then decode one at a time with the card.
• If your answer almost works, read the nudge. A reversed message you typed forwards gets a hint about which way round it was sent.

Help, when you want it

Tuning has two free hints (where to look on the band, and what PHASE does), then a button that turns both dials to the station for you. Decoding has three free hints (the method, some letters, nearly all of it), then a button to show the message. Tuning help shows as a different mark on your share card, and showing the message ends the day as Not today. Neither costs you a streak.

What makes this Morse code puzzle different

A Morse puzzle usually hands you the dots and dashes. Here you earn the signal first. The radio is a real object: a walnut cabinet with a brass front, four glass valves whose filaments warm up as the signal clears, a green scope, a glowing tuning dial and a telegraph key that replays the message from its first letter. Knobs carry on turning after a flick and click through detents. When you solve it, the key taps out R by itself and a paper strip feeds out of the slot with your word typed on it. It runs in the browser, works with a keyboard and a screen reader, and every sound has a visual twin, so it is always playable on mute.

A new signal at your midnight

Each player gets the intercept for their own local date. Your streak counts every finish, and one spare key covers a single missed day. The share card never shows the message.