Website | Puzzle Guidebook | App Manual | Prop Templates | Scenario Outline

Roles: Puzzle Designer, UI & Interaction Designer

Development Time: 3 Months

Team Size: 6

Aesthetic: Tabletop role playing, historical narrative

Platform: Tabletop + Mobile


  • Designing and prototyping the code breaking puzzles: linguistic, mathematical, visual pattern finding.
  • Designing, playtesting, and iterating puzzle difficulty progression.
  • Designing and crafting cardboard physical props and construction templates & manuals.
  • Designing, 3D modelling, and texturing the props’ digital interfaces.
  • Designing thematic and branding materials such as project brochure and poster.
  • Coordinating design dependencies and aligning design goals with the lead and narrative designers.

Project Background

Enigma is a graduate student project at Carnegie Mellon University’s Entertainment Technology Center. The team was approached by Jessica Hammer and Moyra Turkington – designers behind the tabletop role-playing game (TRPG) War Birds: Rosenstrasse – to design a TRPG experience where the players embody the female code breakers residing in Bletchley Park during the WWII period.

The clients’ intention for the project was to explore the design possibilities of technology in the tabletop role-playing genre and potentially launch a crowdfunding campaign to publish the product on the market.

Hence the team was assigned the following three main goals:

  1. Design a code-breaking puzzle,
  2. Augment the experience using modern-day technology,
  3. Document a manual package for authoring additional content.


Since the project dealt with sensitive subject matter, the team first focused on researching the historical facts, events, and any other relevant information. Bletchley Park is the birthplace of the modern-day computers. It is also where significant intellectual inquiry and contribution to the war effort were made by female-majority workforce. And ultimately, its existence and function were kept top-secret during and after the war.

During the first “immersion” week, the team conducted research over a wide variety of mediums. The team interviewed Julia Parsons, an American code-breaker, who was visiting the university at the time. This shed light on her day-to-day life both at work and during personal times. This helped the team paint a vivid picture of the far-away historical figures as real people.

The team also studied the Enigma machine in real life, now securely displayed alongside other WWII devices at the university library. The team examined and studied the artifact’s intricate assembly and its enigmatic design.

To better understand what life in Great Britain was like at the time, the team interviewed Anthony Daniels, a British actor most famously known for his role as C3PO in the Star Wars movie franchise. As one of the visiting scholars at the school, he shared his life experience growing up in the suburbs of Salisbury during the 1950’s. This significantly informed the cultural background of the experience, such as daily routines, forms of expressions, etc.

The team also consumed history articles, puzzle books, and tv shows such as The Bletchley Circle, which depicts the life story of women cryptographers from Bletchley Park post-WWII period.

To study the tabletop role-playing genre, the team conducted case studies of the clients’ previous work and other narrative-driven puzzle experiences such as escape rooms. The team learned how to use meaningful choices to drive the character developments, and how to encourage collaborative problem-solving by distributing unique roles, abilities, and information to each player.


In the first few weeks of development, the team spent time synthesizing research findings and brainstorming a library of ideas. We adopted the following design pillars, which was to make the players feel: 1) Smart, 2) Heroic, and 3) In Character.

The team initially employed a “Diverge” design process where each member individually experimented with one’s ideas. This proved to be successful in generating ideas from different perspectives, but we realized that we needed a high-level narrative scenario to ground our design decisions.

The team chose to base the experience on the Coventry Blitz, a series of bombing raids by the German Air Force on the British city of Coventry. The event was picked for its sense of urgency and the dramatic plot development involving emotional conflicts between the code-breakers and the British government.

Moving forward, the team reorganized itself into a more specialized structure where each member owned a specific facet of the experience. I was responsible for designing the code-breaking puzzles, physical props, and the mobile apps that interfaced with them in some way. We then adapted to Diverge <-> Converge work cycle, where each member works on a specific feature in isolation and periodically circles back with the team. This enabled the team to rapidly ideate, prototype, and iterate game features without being bogged down by dependencies.

Code-breaking Puzzle: Prototype

The design goals for the puzzle were to make the players feel smart, heroic, and collaborate with each other. After an initial study of code-breaking, I concluded that actual code-breaking was too difficult for laymen since it required the professional expertise of linguists and mathematicians. I abstracted code-breaking into a broader definition:

“…an act of linguistic, numerical pattern finding while working with tangible objects.”

Another important design consideration was the puzzle’s scalability and accessibility. The puzzles had to be modular to allow future extensions, and had to be easily printed at home using a regular printer.

Initially, I experimented with a wide range of puzzle formats and mechanics, such as concealed messages in newspapers, blocks with encrypted symbols, etc. Playtesting these early prototypes, however, revealed multiple problems. First, the players felt that the puzzles did not match their expectations of code-breaking, which broke the immersion. Also, the structure felt too isolating, where the players did not have the knowledge to help one another so each just focused on one’s work.

Code-breaking Puzzle: Iteration

Hence, the puzzles had to involve the physical process of drawing on paper, and be centrally structured to encourage communication and collaboration. To better echo the physical and mental processes of code-breaking, I devised the following design principles:

  1. Drawing on Paper with Pencils
  2. Mathematical Pattern Finding
  3. Linguistic Pattern Finding
  4. Visual Pattern Finding

After multiple iterations, I thought of a way to layer these principles onto the same puzzle, starting from a small scale and gradually expanding out to the big picture. Inspired by word-search and crossword puzzles, I adopted a “successive” puzzle-solving process, where a solution offered hints to the deeper layers of the puzzle.

Code-breaking Puzzle: Level Design

Using this layered design approach, I designed a series of puzzles that increased in complexity and difficulty as the players progressed through the story.

For the entrance exam puzzle, the four players – two mathematicians and two linguists – are each given a puzzle with numbers or letters printed on a grid. To solve the puzzle, each player connects the numbers and the letters in ways that make sense. For example, a linguist would form the beginning of a sentence “Your job is…” whereas a mathematician follows a path adding 3 to each consecutive number. Once the individual puzzles are solved, the players compile their drawings onto a single empty grid, which yields that word “PASS” when completed.

The second scene puzzle builds on this gameplay, except now all players are thrown at a single puzzle. This is intended to spark discussion between team members while physically working around one another. The coupling of two mathematicians and two linguists allow them to easily help each other in case one gets stuck. The encryption is more complex, encouraging the players to use the information found along the lines. For example, the completed sentence “Clues are hidden in the leftmost column” will lead the players to the words Event, Date, and Time. In associating this information to the drawing, the players can conclude the hidden message to be BOMB, NOV 14, 15:00.

The fourth scene puzzle, the last of the series, puts a twist by revealing a code name instead. Using the grid as a Bigram substitution table, the players substitute the highlighted lettersK, O, R, N – with their respective x- and y-coordinates, which are then transposed to make the word Coventry.

Physical Prop: Protoype

The design goals for the props were to set the world atmosphere and serve as role-playing objects for the players. Inspired by the WWII-era antiques, I was inspired by the information and communication appliances that the code-breakers used on a daily basis. After the first round of prototyping, I decided on a military radio, a flip clock, and a rotary dial phone, each with a distinct physical silhouette and mechanical function.

Like the puzzles, the props had to be designed for home assembly without the need for special materials or power tools. Using the Nintendo Labo as a role model, cardboard was chosen as the preferred material since it can be commonly found in any household. 

Physical Prop: Iteration

The props were to offer role-playing opportunities for the players, however it was revealed that they felt too stale without the operational functions and hence rarely used. Also, it turned out that the initial assembly design was too complicated which required meticulous craftsmanship. To address these feedback, I embedded the mobile apps directly into the props to emulate their mechanical functions. I also simplified the props’ geometry to significantly lower the assembly difficulty. 

Mobile App: Prototype

The design goals for the mobile apps were to augment the experience with interactivity and to offer the facilitator a remote controller to curate in-game events. Inspired by the electronics’ interfaces of that time, the apps were to offer the players a variety of mechanical functions, such as radio news feed, external phone line, and ambient music.

Another important design consideration was extensibility. By designing each device with a specific functional capability, it gave our clients the flexibility to add additional features in the future. 

Mobile App: Iteration

While the mobile apps were initially envisioned as handheld devices, there were several unresolved issues. First, the idea of using high-tech mobile phones felt out of place. Secondly, they were constantly distracting the players by drawing too much attention to themselves. Their handheld mobility prompted the players to unconsciously fidget with them.

To address these feedback, the apps’ interfaces were changed to match that of 1940’s electronics, and the phones themselves were embedded into the physical props to discourage the players from holding onto them. These “prop apps” were centrally networked with the facilitator’s app, which enabled the facilitator to trigger in-game events like an external phone call. The apps went through multiple design phases, including paper wireframes, low-fidelity mockups, and high-fidelity prototypes, with each answering a specific set of questions.

The visual design of the interfaces was based on readability, where a visual hierarchy would subconsciously indicate the apps’ primary and secondary functions to the players. For example, the radial knob on military radio is the largest UI element and is centrally positioned, whereas the small on/off switch is located at the bottom left corner. Also, they had to be designed at scale with the physical props to achieve an aesthetic harmony.

Playtesting: Diverge & Converge

The team employed the Diverge <-> Converge approach to playtesting in order to get a holistic measure of the entire experience while also rapidly developing the individual elements:  1) puzzles, 2) physical props, and 3) mobile apps.

The playtest sessions for each element was conducted separately and frequently over the development period, which was then occasionally integrated with other elements in 4-hour experience sessions where the players ran through the whole experience. While the two methods yielded different results, this proved to be an effective way to incrementally measure the project’s success and contain the scope within reason.

Final Deliverables

At the end of the semester, the team successfully delivered the project package to the clients that includes:

  1. Branding Materials
  2. Mood Boards & Style Guide
  3. Scenario Outline
  4. Narrative Reference Materials
  5. Code-breaking Puzzles
  6. Physical Props
  7. Mobile Apps
  8. Creation Manuals & Templates

ETC: Open House 2018

The team showcased the project to the general public during the open house at the Entertainment Technology Center. Throughout the day, we hosted over 100 guests who had tons of fun code-breaking !