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 gives you the QEP number and prints the message for you. Hard and Realistic modes are the whole operator's job on the same intercept: read the QEP off the tape, set the wheel pins from the day's pattern sheet, set the start positions, read the punched tape row by row with a telecode cheat sheet, then encipher and send a reply on a fresh line of the book. Hard has you prove each step once and fills in the rest; Realistic leaves all of it to you.

The game is free, needs no account and has no ads or cookies, only an optional coffee link and a newsletter box; 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.