Turing versus Scherbius

The card game

June 1, 2025

The Spark of Inspiration: A Battle of Wits

The game draws its core theme from the monumental intellectual duel of World War II: Alan Turing and his team at Bletchley Park against the formidable Enigma machine, co-invented by Arthur Scherbius. The Enigma was a marvel of engineering, used by the German military to encrypt their communications. Turing’s eventual breaking of Enigma is a legendary tale of perseverance and brilliance, providing critical intelligence that many argue shortened the war.

As portrayed in “The Imitation Game”:

Alan Turing: We need your help, to keep this a secret from Admiralty, Army, RAF, uh…as no one can know, that we’ve broken Enigma, not even Dennison.
…
Alan Turing: While we develop a system to help you determine how much intelligence to act on. Which, uh, attacks to stop, which to let through. Statistical analysis, the minimum number of actions it will take, for us to win the war - but the maximum number we can take before the Germans get suspicious.

This delicate dance of discovery, exploitation, and secrecy is precisely what I wanted to capture. To win as ‘Turing’ in this game, you must not only break a code but also exploit your knowledge subtly, without revealing the full extent of your breakthrough.

This was originally Nick Johnstone’s (aka Widdershin) idea. I’ve slightly changed t he game mechanics, and added proper encryption.

The Game: An Overview

“Turing vs Scherbius” is a two-player card game where one player takes on the role of Turing, the codebreaker, and the other plays as Scherbius, the encrypter. The ultimate goal for both is to be the first to accumulate a target number of Victory Points.

How does it work?

The game unfolds over a series of rounds, and each round consists of multiple battles. In each battle:

  1. Both players commit cards from their hand. These cards have numerical values.
  2. The player who commits the higher total sum of card values wins the battle.
  3. Winning a battle earns you a reward – either Victory Points or new cards to bolster your hand.

Sounds simple, right? But here’s where the Enigma—and the mind games—come in.

The Scherbius Player: The Keeper of Secrets

Playing as Scherbius, you are the master of encryption:

  • Resource Advantage: You begin the game with more cards (scherbius_starting) and receive more new cards each round (scherbius_deal), representing your established machinery.
  • The Enigma Machine: When you decide which cards to play in each battle (your strategy), Turing doesn’t see your raw plays. Instead, your card values are first passed through an encryption cipher (a two-rotor polyalphabetic substitution cipher, in game terms, our EasyEnigma). Turing only sees this encrypted version of your moves.
  • Changing the Keys: As Scherbius, you have a crucial ability: you can spend some of your accumulated Victory Points (encryption_cost) to change the encryption settings. This forces Turing to start their codebreaking efforts anew, disrupting their plans.

The Turing Player: The Challenger

Playing as Turing, you are the underdog:

  • The Information Disadvantage: You start with fewer cards (turing_starting) and gain fewer each round (turing_deal). However, when Scherbius makes their moves, you see their intended plays, but they are scrambled by the current encryption.
  • Breaking the Code: Your primary challenge is to deduce the current encryption scheme. By observing the encrypted values Scherbius plays and comparing them to the outcomes of battles and the rewards on offer, you can start to piece together the cipher.
  • Strategic Deception: Once you have an idea of the encryption, you face the “Imitation Game” dilemma: how much do you exploit this knowledge? If you win too decisively or too obviously, Scherbius will know their code is compromised and will likely spend points to change it, setting you back. You must carefully choose which battles to win and how.

Dive In!