Once a game idea has been settled on, the next phase of the concept stage is to develop a prototype. In playcentric design, as described by game designer Tracy Fullerton, the player experience is placed at the center of the process. A game isn’t evaluated by how clever its mechanics seem on paper, but by how it feels when played. This means prototyping and playtesting happen early and often, to shape the design through direct experience.
Types of Prototypes
Prototyping is a critical step in game development, allowing designers to explore ideas, test mechanics, and evaluate player engagement before committing significant time and resources. Prototypes serve as experimental models of the game, providing insight into what works, what doesn’t, and what might need to be refined.
There are two main types of prototypes: physical and digital, each serving different purposes in the design process.
Physical Prototype
A physical prototype is a working model of the game used to quickly test feasibility and engagement factors. By interacting with the game in a hands-on way, designers can quickly evaluate core elements without the overhead of digital production.
Best for Testing:
- Game Balance
- Core Mechanics
- Player Engagement
Digital Prototype
If the final output of the game is to be digital, a digital prototype will eventually be required to fully test the systems and interactions. Digital prototypes simulate the game in software and are particularly useful for games that will ultimately be digital. They allow designers to test mechanics, systems, and technology integration that cannot be fully evaluated with physical prototypes.
Best for Testing:
- Technology Integration
- Complex Systems and Interactions
- Kinematics and Physics
Exploring Physical Prototypes
Physical prototypes are sometimes called paper prototypes because these earliest prototypes are made not as digital games, but with pen and paper.
You might be thinking, how in the world can one create a physical prototype for a complex video game idea? The goal of a physical prototype is to provide only a rough idea of how the game or parts of the game will function and serves as a blueprint for game development.
Physical Prototype of an FPS
Even a first-person shooter can be paper-prototyped. While you obviously can’t test the smoothness of the controls or the feel of aiming and shooting, you can test core systems, for example:
- Represent the player and enemies with tokens on a simple paper map.
- Use dice to introduce randomness, such as how many enemies spawn in a space each turn.
- Track resources like ammo, health, or abilities with cards or counters.
- Test balance: Are there too many enemies for the ammo or resources available?
- Test engagement: Does the pacing keep players challenged and interested?
- Observe player decisions and experiences.
Building Prototypes
Physical prototypes are a crucial first step in bringing a game concept to life and should be created early in the concept stage. The process can be approached in clear, practical stages, following an iterative loop similar to other design approaches, such as the scientific method: build, test, observe, and refine.
Prototyping Steps
Step 1: Lay the Foundation
- Build a representation of the key gameplay: challenges, choices, and consequences.
- Identify the basic game objects, such as settings, units, and resources.
- Establish the game mechanics (rules and procedures).
- Develop the core mechanics—the repeating player actions that drive the game.
Units
Units represent players’ characters. Use items like paper cutouts or peg people that fit within a single grid cell, have an obvious forward direction, and are distinguishable from other units.
Step 2: Build the Framework
- Prioritize what is most important in the game.
- Decide which rules are essential.
- Keep a clear distinction between features and rules.
Features vs Rules
Features enrich the game but don’t alter core mechanics; rules define how the game functions.
Step 3: Add Finishings
- Define all necessary rules for the game.
- Test the validity of each rule.
- Add or remove rules as needed.
Not every rule is critical to a game
Avoid adding non-essential or overly complex rules that do not meaningfully affect gameplay.
Step 4: Refinement
- Play through the prototype. Is the game compelling? What makes it engaging or not?
- Assess and refine mechanics, rules, and features as needed.
- Evaluate new ideas and implement only if they improve playability or engagement.
Playtesting Drives Prototyping
Playtesting is continuous throughout prototyping: each test reveals what works and what needs revision. Based on these insights, the prototype is updated and tested again, repeating the cycle until all key measures are satisfied, and production can begin.
Evaluating Prototypes
Once a physical prototype is developed, designers can begin examining the foundations of their game—the elements that shape how it feels to play. In playcentric design, prototypes are evaluated using four measures: functionality, completeness, balance, and engagement. However, I have chosen to reframe these as I’ve reframed them into the following measures for clarity: playability, gameplay, balance, engagement, and completeness.
Playability
Playability reframes functionality. A game may be technically functional, but that doesn’t always mean it’s playable. For example, I once had a group of students create a digital turn-based card game where the mechanics worked correctly, but the interface made it unclear whose turn it was. The game “functioned,” but it wasn’t actually playable. Playability ensures that players can clearly understand and interact with the game’s mechanics.
- Game Mechanics: The formal rules and procedures that govern play.
- Core Mechanics: The repeating player actions that drive the game loop.
Game vs Core Mechanics
These are sometimes confused with overall game mechanics but focus on the essential gameplay loops. For example, in a first-person shooter,
- Core mechanics might be aiming, shooting, and reloading, the repeated actions that drive player decisions,
- Game mechanics also include rules about scoring, enemy behavior, and level objectives.
Gameplay
Gameplay builds on playability and starts to reveal balance and engagement. It consists of the player’s overall experience, shaped by the challenges, choices, and consequences that emerge from interacting with the mechanics.
Balance
Balance ensures fairness, challenge, and meaningful decisions. It can be tested throughout prototyping by adjusting rules, resources, or difficulty curves to avoid overwhelming or trivializing player actions.
Engagement
Engagement measures whether players want to keep playing. While “fun” is subjective, what excites one person might bore another; engagement is a more reliable gauge of investment. If players are motivated to continue, the design is on the right track.
What is “Fun”
What makes a game “fun” can be surprisingly hard to define. For example, I might find solving math problems exciting, while my sister would probably rather have a root canal than do any kind of math. While “fun” is subjective, what excites one player may bore another; engagement provides a clearer gauge of whether the game keeps players invested and motivated to continue playing.
Completeness
Completeness identifies when systems or features are developed enough to move forward. In prototyping, this doesn’t mean the entire game is finished, but rather that a specific feature or mechanic is sufficiently fleshed out to test in the next stage of development.
By combining physical prototyping with attention to mechanics, gameplay, and engagement, designers can identify what works, what feels confusing, and what keeps players motivated, long before moving to digital prototypes or final builds.
Rapid Prototyping
Physical prototypes are a natural form of rapid prototyping. These quick, low-fidelity versions of a game allow designers to experiment, test interactions, and evaluate playability and engagement without investing significant time or resources. As indie developer Mark Barrett explained at the 2017 Game Developers Conference, a rapid prototype is essentially a rough draft or first experimental version of a game, designed to learn quickly, explore feasibility, and identify potential problems early.
Barrett highlights several key principles for effective rapid prototyping:
- Purpose: Rapid prototypes are especially useful for developers with limited resources or experience, acting as “cross-training” to improve skills, satisfaction, and productivity.
- Minimum Viable Interaction (MVI): Focus on producing a core behavior or interaction rather than a polished product, allowing designers to fail fast and learn efficiently.
- Goal-Setting: Use SMART goals (Specific, Measurable, Attainable, Relevant, Time-bound) to clarify important outcomes and guide prototyping decisions.
- Scope with Humility: Keep prototypes manageable by recognizing limitations of time, resources, and skills. Barrett advises: “Start where you are, use what you have, and do what you can.”
- Balanced Vision: Tools like the Core Diagram help map a game from the central mechanic outward, including core and secondary mechanics, progression, system, and narrative.
- Flexible Process: Adapt methods that suit your workflow, drawing from Agile, Lean Startup, or one-week Sprints. Wireframing tools like Proto.io or Balsamiq can create interactive mock-ups without coding.
- Experience: Participate in a game jam. Even 24 hours of building a game provides practical learning that surpasses theory, reinforcing rapid iteration, collaboration, and testing.
Rapid Digital Prototypes
While rapid prototyping is often discussed in terms of physical prototypes, digital prototypes are also valuable for testing mechanics or systems that exist only in software. They allow designers to explore interactions, rules, or narrative flow without building the full game. For example, Twine can be used to quickly test dynamic storylines before moving to the final game engine.
Blockout Levels
Another type of digital prototype is the blockout level, sometimes called grey-box, white-box, or blockmesh. A blockout is a rough layout of a game level using basic geometry, simple meshes, or placeholder assets. While the term “grey-box” is often used, this does not mean the level is literally all gray; can you imagine how disorienting that would be to play? Instead, the level is made up of colored boxes or temporary stand-in assets. The key point is that these levels lack final graphics, helping designers focus on gameplay rather than visual polish.
When creating blockout levels, the goal is to test player engagement, challenge flow, and level layout. Detailed textures, lighting, and final art are intentionally left for later stages, allowing designers to iterate quickly on how the level feels and plays.
In short, rapid prototyping, whether physical or digital, should emphasize speed, experimentation, and continuous learning. By focusing on interactions rather than polished products, setting clear goals, scoping realistically, and iterating quickly, designers can refine ideas efficiently and prepare for later development stages.
Productive Prototyping
Rapid prototypes provide valuable insights, but their usefulness depends on how they are designed and tested. Productive prototyping ensures that each iteration yields meaningful feedback, guiding game design decisions efficiently. Jesse Schell, in The Art of Game Design: A Book of Lenses, offers several practical tips for making prototypes productive, whether physical or digital.
Key Tips for Productive Prototyping:
- Answer a Question: Each prototype should target a specific question: Is it fun? Technologically feasible? Does the premise make sense?
- Build Physical Prototypes: Physical prototypes are the fastest way to test game ideas, explore interactions, and evaluate playability. (See Rapid Prototypes)
- Forget Quality: Prototypes are rough drafts. Focus on functionality and testing one idea at a time rather than aesthetics or polish.
- Don’t Get Attached: A prototype is a starting point, not the final game. Be ready to revise or discard ideas based on testing and feedback.
- Prioritize Prototypes: Test unique or high-risk features first. For example, in an FPS with a puzzle element, prototype the puzzle mechanics before standard shooter features.
- Parallelize Prototypes: Teams can work on multiple prototypes simultaneously, for instance, one group testing puzzle mechanics while another evaluates weapons balance.
- Build a Toy First: Start by prototyping the “toy” of your game, the interactive core without full challenge. Gameplay challenges and mechanics emerge as the prototype is refined.
Productive Digital Prototypes:
- Pick a Fast Loop Engine: As discussed in the Digital Prototypes section, digital rapid prototypes use temporary tools to test interactions quickly. Choosing the right engine or tool speeds up iteration and feedback without committing to full development.
- It Doesn’t Have to Be Interactive: Features can be represented through storyboards or animatics to prioritize testing key interactions without coding every element.
- Seize Opportunities for More Loops: Even short prototypes can be iterated repeatedly. Take advantage of every chance to test, revise, and improve.
By applying these principles, designers can extract the maximum value from each prototype, ensuring rapid learning, focused testing, and efficient development before moving on to more detailed or final versions of their games.
Why Prototypes Matter
Far too often, game designers underestimate the value of developing physical prototypes and skip this vital step in pre-production.
Physical prototypes provide early insights into a game idea, revealing what works, what doesn’t, and which direction the design should take. They also offer the earliest opportunity to playtest the game with others, gathering feedback that can shape mechanics, gameplay, and engagement before committing to digital development.
A notable example comes from Halfbrick Studios, the creators of Fruit Ninja and Jetpack Joyride. As chronicled in a video by People Who Make Games, the team developed a simple paper prototype for a new game idea, and it went horribly wrong. Yet this “failure” was invaluable: it highlighted critical issues early, helping the team refine their concept and avoid costly mistakes in later development.
Ultimately, physical prototyping is not just a step in production; it’s a playcentric, iterative process that guides designers toward engaging, balanced, and playable games. Skipping it risks investing significant time and resources into ideas that haven’t been properly tested in the real world.
Key Terms
Playability – The degree to which a game can actually be played; mechanics are clear, actions are executable, and players understand what to do.
Game Mechanics – The formal rules and procedures that structure the game and enable player actions.
Core Mechanics – The fundamental, repeating actions that drive the main gameplay loop (e.g., moving, drawing cards, shooting).
Gameplay – The overall experience created by interacting with the mechanics, including challenges, choices, and consequences.
Balance – The fairness and meaningfulness of decisions, strategies, resources, or roles within the game.
Player Engagement – The player’s desire to continue playing; a measure of motivation and “fun.”
Completeness – The degree to which systems or features are developed enough to be tested or considered ready for production.
Core Diagram – Designed by Charmie Kim, the Core Diagram visualizes a game’s structure with the core mechanic at the center, other mechanics layered around it, and the narrative on the outside