How to Prepare a Technical Design Document for Games

In the game development process, well-prepared documentation is critically important for a project’s successful progress. Among such documents, the technical design document serves as a guide for the development team by detailing the game’s technical infrastructure and how it will be built. In this article, I will answer the question “what is a technical design document” and will examine step by step “how to prepare a technical design document.” By focusing specifically on how this document should be created for game projects, we will provide a comprehensive guide for both intermediate and professional game developers.

What Is a Technical Design Document?

A technical design document is a written document that defines in detail how a game project will be developed from a technical perspective. In terms of content, it has a structure similar to the game design document (GDD), but its focus is different: while the game design document describes what the game’s functionalities are, the technical design document explains on a technical level how those functionalities will be implemented. This document is usually written by the lead programmer or technical lead and serves as a guide for the other programmers on the team.

In a sense, the technical design document is the technical “equivalent” or complement of the game design document. In the game design document, general concepts and design details of the game are defined from the user’s perspective, whereas the technical design document defines the game’s architecture from the developer’s (implementer’s) perspective. For example, the design document includes the features the game contains and a description of the experience; the technical design document, on the other hand, lays out the technologies, architectural approaches, and processes that will be used to implement those features. These two documents are prepared separately, but typically key technical information is also summarized within the design document. For instance, a GDD might include a section titled “Technical Data” that provides details such as the game engine to be used, programming language, technical requirements of the target platforms, and anticipated system specifications. Nevertheless, it should be remembered that these technical details need to be addressed in a much more detailed manner in a separate technical design document.

The scope of a technical design document can vary from project to project, but generally it includes: a general description and scope of the project or feature, technical requirements and specifications, details of the system architecture and its components, algorithms or methods to be implemented, tools and technologies to be used, possible dependencies, and potential technical risks along with their mitigations. In other words, this document is like the game’s technical “blueprint”; it ensures all members of the development team are on the same page (share a common understanding) and provides a clear roadmap for how to build the project.

Technical design documents are living documents, meaning they are updated as the project progresses and requirements change. Throughout the development process, new details are added or changes are made as needed. Thus, the document continuously reflects the project’s current status and technical direction. The technical design document is primarily prepared for the development team, but it can

also be presented to project stakeholders, investors, or publishers if necessary. Publishers in particular often want to see a project’s technical feasibility and planning before investing in a game; therefore, a well-prepared technical design document can also be useful for instilling confidence in external stakeholders and demonstrating the project’s value.

Importance of the Technical Design Document

Preparing a correct and clear technical design document is not a luxury in game development projects, but often a necessity. This document strengthens internal team communication because it establishes a shared understanding of the project’s technical details. By ensuring that all team members (designers, programmers, artists, etc.) reference the same technical information, it prevents misunderstandings and conflicts that might otherwise arise later. The technical design document also facilitates coordination between different disciplines (e.g., the design and engineering teams), so that everyone knows the game’s technical constraints and capabilities and works in harmony. As a result, the project’s quality increases and the development process becomes more efficient.

The absence of good technical documentation can introduce serious risks in projects. According to research, insufficient communication and unclear requirements are among the primary causes of project failures. Technical design documents help minimize these risks by clarifying the technical requirements and solutions in a project. For example, a study by the Standish Group indicates that lack of communication and unclear requirements have a significant contribution to project failures. Similarly, research by IEEE has shown that clear and comprehensible documentation can reduce the risk of project failure by up to 20%.

Moreover, a comprehensive technical design document improves project planning as well. Anticipating technical challenges and needs at the start of the project prevents surprises later on. Since the team knows from the outset which technologies will be used, potential bottlenecks, and solution strategies, they can make more accurate time and budget plans. This is vitally important especially for large, professional teams; because even if team members change (for example, a new developer joins the project), they can quickly get up to speed thanks to the technical document. In short, the technical design document is a roadmap and an insurance policy that guides the project to success.

How to Prepare a Technical Design Document?

When preparing a technical design document, it is necessary to follow a systematic and detail-oriented approach. Below, we outline the basic steps of preparing a technical design document for a game, each discussed in turn:

Create the General Description and Scope of the Project:

First, at the beginning of the document, write a brief overview of the project or the related feature. In this general overview section, you should briefly describe what the game is, its concept, and its core purpose. Next, list basic technical context information such as the game engine used, programming language, and target platforms. For example, clearly indicate in this section which programming languages and libraries the project will use, the version of the game engine to be used, any third-party software or tools, the platforms on which the game will run, and the estimated system requirements. This way, someone reading the document (for instance, a newly joined team member or an external stakeholder) can quickly grasp both the concept and the technical framework of the game.

Define the Technical Goals and Requirements:

Clarify the technical goals that the project aims to achieve. These goals include the technical success criteria for the features outlined in the game design. For example, goals such as “realistic lighting and shadow system,” “advanced AI behaviors,” or “support up to 100 players” can be set. Write down the requirements for each goal: hardware requirements (minimum/recommended PC specs, supported platforms), software requirements (operating system, SDK versions, etc.), performance criteria (target frame rate, resolution, latency) and similar items should be included in this section. Technical goals serve as guiding benchmarks for the team; they ensure that everyone keeps these objectives in mind when writing code or producing content. For instance, if a goal of “complex AI” has been set, then the necessary AI algorithms and processing budget for that feature are planned in advance. Clearly defining technical requirements prevents future incompatibilities and sets the bar for the project’s success.

Identify the Technologies and Tools to Use:

In this step, detail the technological infrastructure chosen to develop the game. List all components such as the game engine (e.g., Unity, Unreal Engine, or a proprietary engine), programming language(s) (C++, C#, Python, etc.), libraries or SDKs to be used, and any database or server technologies (if required). However, merely listing them is not enough; you should also briefly explain why each technology was chosen and how it will be used in the project. For example, you might write statements like: “The Unity game engine will be used for the core of the game because it supports both 2D and 3D and the team has extensive Unity experience. For networking, the Photon Networking library was chosen because it allows rapid multiplayer prototyping without requiring server infrastructure.” This section should also mention external tools: list the toolset that will be part of development, such as the version control system (Git, SVN, etc.), project management tools ( Jira, Trello, etc.), 3D modeling or 2D graphics tools (Blender, Photoshop), and audio editing software. If applicable to the team, a coding style guide or design patterns to follow in code can also be referenced in this section. The purpose of the technology and tools section is to define in advance all the technical components that will be used during development, ensuring that team members work in harmony.

Define the System Architecture and Game Components:

This stage forms the backbone of the game’s software architecture. Detail the main components of the game and how they relate to each other. First, present a high-level view of the game’s systems with an overall architecture diagram or schematic (for example, draw the main components such as the game loop, rendering system, physics system, audio system, AI, user interface, network module as boxes and show data flows with arrows). Then explain each main component under subheadings. For example:

• Game Loop and State Management: What happens when the game starts, during gameplay, and when the game ends? How will the main game loop operate; will there be a frame rate cap, and how will the update loop and render loop be managed?

• Graphics/Rendering System: Details such as the graphics API to be used (DirectX, OpenGL, Vulkan, etc.), the target resolution and frame rate, the lighting model, shading techniques, and post-processing effects. For example: “Real-time shadows and global illumination will be used for lighting; for this, Unity’s URP pipeline was chosen.”

• Physics and Collision: What will be used as the physics engine (e.g., PhysX, Havok, or Unity’s built-in physics)? Which physics features will be active (gravity, friction, collision layers, etc.), and what are the rules of physical interaction for the characters/world?

• Artificial Intelligence (AI): Topics such as enemy or NPC intelligence, pathfinding algorithms (e.g., A*), decision-making mechanisms, use of state machines or behavior trees, etc. If the game requires very complex AI, plan the architecture of the AI system in detail in this section.

• Inventory/Character System: How will the player character’s and NPCs’ attributes, inventory management, ability system, etc. be implemented?

• User Interface (UI): The overall architecture of the UI, the menu system, HUD structure, and which technology will be used (e.g., Unity UI Toolkit, Unreal UMG).

• Networking and Multiplayer (if applicable): If the game will have multiplayer, is it using a client-server architecture or peer-to-peer? Critical topics such as server infrastructure, synchronization strategies, and lag compensation methods should be specified.

For each subsystem, if possible, provide an explanation at the class or module level. For example, for AI you might include an architectural description such as: “There will be classes like EnemyController, PatrolManager, AIDecisionTree; system X will send messages to system Y.” Technical depth is important in this part: if necessary, use UML class diagrams, flowcharts, or sample pseudo-code snippets to support your explanation. In summary, the system architecture section lays out the game’s internal structure and how the pieces connect to each other. A reader should be able to envision how it will work technically after reviewing this section.

Establish Coding Standards and Development Workflow:

In professional teams, writing consistent and clean code is very important. Include a section in your technical design document on the coding standards that should be followed throughout the project. This section covers topics such as variable and function naming conventions, class structures, file/ directory organization, and code commenting practices. For example, you might list team-adopted rules like: “All class names will be in CamelCase, constants will be written in all caps, magic numbers will not be used, important functions will be commented in Javadoc style.” Consistent coding standards make all programmers’ code within the team more readable and maintainable.

This section can also usefully provide details about version control and workflow. Which version control system will be used (Git, Mercurial, etc.) and what will the repository structure be? For example, you could outline a branching strategy such as: “The Git flow model will be applied; no code will be written directly to the main branch, a feature branch will be created for each feature and, after testing, merged via a pull request.” You should state whether code reviews will be conducted as part of the process, and if so, who will be responsible for them. The build and deployment process should also be defined: Are Continuous Integration (CI) tools being used? Will nightly/automated builds be performed? How and how often will test builds be shared within the team? For instance: “Every Friday, an internal playtest build will be prepared and delivered to the QA team.” Defining such workflows helps maintain discipline and order within the team. Especially in large teams, documenting these standards and processes increases efficiency and reduces the likelihood of errors by ensuring everyone follows the same methods.

Outline Technical Risks and Solution Strategies:

Every game project can contain uncertainties or risks from a technical perspective. In this step, list the potential technical risks you anticipate and note possible solutions or preventive strategies for each

one. Risks can include any technical issues that might jeopardize the success of the project. For example:

• Performance risk: “The open world map is very large; if memory optimization is not done, out- of-memory issues could occur.” Solution: “A streaming system will be implemented so that regions are loaded as needed, and unused objects will be unloaded from memory.”

• Network latency risk: “In multiplayer mode, high ping values could affect the game.” Solution:

“Lag compensation techniques (client-side prediction, server reconciliation) will be integrated.”

• Lack of technical expertise risk: “Our team doesn’t have someone very experienced in AI, so a complex AI might not be developed in the desired timeframe.” Solution: “Simplify the AI modules or seek consultation, and plan a longer R&D period.”

• Integration risk: “What if the chosen external library (for example for networking) doesn’t work as expected?” Solution: “Validate the library beforehand with a prototype, and keep alternative open-source libraries on standby.”

Writing down such mitigation plans for each risk item ensures that you are prepared before problems arise. This section is especially valuable for project managers and technical leads, because formalizing risk management in writing allows for more realistic time and resource planning. It also instills confidence in the rest of the team by conveying the message, “We are aware of these challenges and have a plan ready.” Remember, no document can eliminate all uncertainties, but being mindful of risks and acting accordingly greatly increases the chance of project success.

Set Performance Targets and Outline an Optimization Plan:

Technical success in games is often tied to performance criteria. Therefore, it is recommended to include a section for performance targets in your technical design document. Clearly specify metrics such as the target frame rate (FPS), resolution, bandwidth usage (for online games), input latency, and the like. For example, you could set targets like: “For PlayStation 5: 60 FPS locked at 4K resolution; for mid-range PCs: 60 FPS at 1080p.” Battery consumption or memory usage targets for mobile devices may also be important.

In addition to performance targets, list the optimization techniques you plan to use to reach those targets. This part may be more technical: for example, you can include items like “Use GPU instancing,” “Distant objects will be rendered with a lower polygon count via an LOD (Level of Detail) system,” “Use compressed formats for audio and implement an object pool for memory optimization.” If the project is in an early stage, some optimizations can be noted as “to be done later” depending on their criticality, but at least it shows awareness. This portion of the technical design document also forms the basis for profiling work as the game develops. It would make the documentation very professional to also specify at which points performance limits will be tested (stress test plans) and with which tools (Unity Profiler, Unreal Insights, memprof, etc.) measurements will be taken.

In conclusion, the performance section establishes a common quality standard within the team by defining the measures and targets that will ensure the game runs smoothly and stably.

Review the Document and Keep It Updated:

Writing the technical design document is not the end of your job – on the contrary, you should implement a review process to ensure the document’s accuracy and clarity. First, ensure that everyone on the team reads the technical document; all developers and relevant team members should review the document and provide feedback. If possible, someone with sufficient technical knowledge from outside the project, or someone not on the team, can also read the document to check for consistency and clarity. This way, any points the author overlooked or ambiguous expressions will be revealed.

Gather the feedback from the team and revise the document with the necessary corrections. Remember that the technical design document needs to be kept alive throughout the development process. As the project progresses, new features may be added, technologies may change, or assumptions may be updated. It is critically important to update the document when such changes occur; otherwise, the document will turn into a piece of paper that does not reflect reality and ends up forgotten. As a good practice, you can add a version number and date to the document and update it with each major revision. For example: “Technical Design Document v1.2 – Update: Network architecture section reorganized, 15/07/2025.” This way the team knows which version they are reading.

Finally, preparing and updating the technical design document requires teamwork. Even if one person wrote it initially, the entire technical team should take ownership of the document. Create an open environment where everyone can contribute when needed (for example, if the document is on an internal company wiki, team members can propose edits). This sense of shared ownership not only improves the quality of the document but also strengthens communication within the team. In short, never approach the technical design document with a “write once and forget” mentality; view it as a living document and work with it throughout the project.

Sample Technical Design Document Template

To understand more concretely how a technical design document created by following the above steps might look, a typical template structure is presented below. Of course, every project is unique and the document structure can vary according to its needs, but in general a comprehensive technical design document can consist of the following sections:

• Title and Version Information: The document’s name (e.g., “Game X – Technical Design Document”), the author(s), date, and version number.

• Introduction (Purpose and Scope): A brief explanation of what this document covers and its purpose. It specifies which project’s technical design this is and defines the target audience (e.g., is it only for the internal team or will investors/publishers also read it?).

• Project Summary: A short summary of the game’s core concept and gameplay. This section contains high-level information taken from the game design document so that technical readers can understand the context of what the game is.

• General Technical Framework: Fundamental technical information such as the game engine, programming language, platforms, and target hardware. For example, items like “Unity 2021 HDRP, developed in C#, target platforms PC/PS5, minimum system requirements: …” can be listed.

• Technical Goals: The project’s critical technical success criteria and objectives. For example, “Real-time ray tracing for lighting,” “Support for 200 concurrent players on the server,” “Maintain 90+ FPS on VR platform,” etc.

• Technical Requirements and Constraints: Hardware and software requirements (e.g., “4K will be supported on Nvidia RTX 3080 and above”), standards that must be followed (e.g., console certification requirements), compatibility needs, scalability requirements, etc.

• System Architecture: The architecture of the game’s main components. This section can be divided into sub-sections:

• Architecture Overview: A schematic view of the entire system, list of the main modules.
• Game Loop and States: Game start/end, state transitions.
• Graphics System, Physics System, Audio System, AI System, Inventory/Combat System, Network System: Include those that are relevant, and open a sub-section for each selected system describing its architecture and key technical details.

• Data Structures and File Formats: Definitions of important data structures to be used in the game (e.g., “The CharacterStats struct contains the following fields: …”), the database schema (if any), or custom file formats (if used). For instance, if your map file format is custom, it is explained here.

• Code Organization and Standards: The project’s folder structure, and if it uses a layered architecture, the definition of each layer (e.g., a modular structure like “Core, Engine, Game, UI”), and a summary of naming and coding standards. Important rules can be listed one by one as a reference for developers.

• Tools and Workflow: Explanation of the tools and processes used in development, such as the version control system (e.g., Git) usage strategy, continuous integration (CI) processes, automated tests or build scripts, issue tracking tools, etc.

• Technology and Library List: A list of all third-party libraries, SDKs, and services to be used in the project. For each, specify the version information and what it is used for.

• Technical Risks and Solutions: A list of the identified risk items along with their solution plans (it is common practice to format this section as a table with columns like “Risk – Impact – Likelihood – Solution”).

• Test and Quality Plan: How the technical tests of the game will be conducted, which tools will be used (e.g., performance testing tools), the process to follow in case of bugs, and whether there will be automated tests — these are quality assurance topics. (Note: This section may not always be included in the technical design document, but some teams incorporate a technical test plan here as well.)

• Performance Targets and Optimization Notes: The targets for frame rate, memory usage, load times, etc., and a summary of the optimizations planned to achieve these targets.

• Conclusion and Future Notes: A brief evaluation, emphasizing that the document is a living document, along with notes on points that will need to be updated in the future. For example, a

note like “The network code is still in prototype stage, so this section will be updated later” can be added.

• Appendices: If necessary, detailed class diagrams, schematic drawings, a glossary of terminology, or references to sources can be included in this section.

Conclusion

A technical design document is like a recipe in a game’s kitchen – it explains step by step how to cook a dish (the game) with the ingredients (technologies) at hand. In this article, I answered the question of what a technical design document is and discussed in detail how to prepare a technical design document for games. A well-planned and well-written technical document makes it easier for professional game developers in particular to complete their projects on time and at the target quality. In conclusion, the effort spent preparing this document pays off many times over in the later stages of the project. Let us not forget that behind great and successful game projects, in addition to creative ideas, there is solid technical planning and a discipline of documentation. By following this guide, you too can create strong technical design documents in your own projects and secure your game’s development process.