Lorenz

About Lorenz

Lorenz is a daily codebreaking game from DEXM Labs, the one-person studio that also made the radio game Skywave and an Enigma machine game. It recreates the Lorenz SZ40/42 cipher attachment, the machine German High Command used to send enciphered teleprinter traffic by radio and that Bletchley Park codenamed Tunny. The wheels, cam counts, tape and teleprinter alphabet follow the wartime sources, while the cam patterns, codebook and messages are made up for the game.

Every player gets the same intercept on the same UTC day, and a new one arrives at 00:00 UTC. The round opens with the QEP number the operator sent in clear before the message. You look that number up on the day's page of the QEP book, which gives a start position for each of the twelve wheels: five psi, two motor and five chi. Some lines in the book are smudged, so for a damp figure you can only read the last digit and have to try the positions that end in it. Set the wheels on the 3D machine, press Decode the tape, and the teleprinter either prints the message or prints garbage.

A correct decode is worth 1,000 points and each wrong try costs 150, with a floor of 100. Points also pay for hints: checking one wheel, revealing a character or reading the smudge. Normal mode prints the message for you. Hard mode has no printer, so you read the punched tape row by row with a telecode cheat sheet, then encipher and punch a reply on a different line of the book. Realistic mode adds setting every wheel's pins by hand from the day's pattern sheet.

The game is free, needs no account and has no ads or cookies; progress, streaks and points are kept in your browser. A Practice mode gives random settings, an Encipher tool and a chi-only mode that matches a printable model of the chi wheels. It suits players who like the history of codebreaking and want a daily puzzle that is more machine than word game.

How to play Lorenz

1. Press Play today's round to open the day's intercept.
2. Read the QEP number at the top: the number the operator sent in clear before the message.
3. Find that number on the QEP book page and note the start position for each of the twelve wheels, in machine order: five psi, two motor, five chi.
4. Where a figure is smudged, only its last digit is readable, so pick a position that ends in that digit.
5. Set each wheel by clicking its arrows, dragging the number or typing it.
6. Press Decode the tape (or the D key) and read what the teleprinter prints; if it is garbage, find the wheel that is out and try again.

Screenshots

Tips

• If the first few letters come out right and then turn to garbage, the chi and psi wheels are probably right and a motor wheel is wrong, since the motors only decide when the psi wheels step.
• Running the exact same wrong settings again costs nothing, so a wrong guess is only charged once.
• Set the teleprinter speed to Visual demonstration to watch each character pass through the chi, psi and motor wheels on the machine.
• In hard mode, use the reading aid: punch the holes you see on a row and the matching line lights up on the cheat sheet.

Questions