Writing a Game Design Document (GDD) for Mobile Games

Writing a Game Design Document (GDD) for Mobile Games

Without a GDD, your mobile game team works blind. The artist draws, the developer codes, the marketer plans—each with their own version of the game. A month later, mechanics don't align, UI doesn't fit in the Safe Area, and monetization doesn't cover CPI. We write a Game Design Document that solves these problems before development starts. Our experience: over 5 years in mobile game development and dozens of GDDs for projects ranging from hyper-casual to midcore. Each document is reviewed with your team and adapted to your tech stack (Unity, Godot, Cocos Creator) and target platform (iOS, Android).

A bad GDD: 40 pages of inspiring text with no numbers or diagrams. A good GDD: the artist understands the style from the moodboard and color table, the developer from state diagrams and numeric parameters, QA from the acceptance criteria checklist for each feature. That's a working document, not a marketing brochure.

What is a GDD and why is it indispensable?

A Game Design Document (GDD) is the single source of truth for the entire team. It captures all key decisions: from genre and mechanics to monetization and technical constraints. In mobile development, where iterations are short and budgets limited, a GDD protects against misunderstandings. Fact: a 4-person team without a GDD lost 2 weeks on rework because the artist, developer, and marketer worked with different visions. A GDD written in 2 days would have saved 2 weeks—that's 7 times faster.

How is a mobile game GDD structured?

The mobile game GDD differs from a PC/console document—it's more compact, focuses on touch interaction and mobile constraints, and includes a monetization section from the first page (that's not shameful, it's market reality).

Overview and Concept

One paragraph: genre, target audience, USP (unique selling point). References: 2–3 existing games with specific indication of what we borrow and what we do differently. Moodboard: 10–15 images of visual style.

Not "an adventure game in a fantasy world." Instead: "a match-3 with RPG progression in the style of Puzzle & Dragons, but with asynchronous PvP and no energy mechanic."

Core Mechanics

For each mechanic: name, 2–3 sentence description, user story ("as a player, I want X to Y"), state machine diagram, input events (tap, swipe, hold), parameters with default values and allowed ranges.

Example of parameters for a "throw" mechanic in a physics puzzle:

throw_power_min: 200 [100-400]
throw_power_max: 1500 [800-2500]
gravity_scale: 1.2 [0.8-2.0]
bounce_factor: 0.6 [0.3-0.9]
max_trajectory_points: 20 [10-40]

These parameters are ScriptableObject in Unity. The game designer can change them without a programmer.

UI/UX Specification

Wireframes for each screen—not final design, but element layout, tap target sizes (minimum 44×44pt per Apple HIG), information hierarchy. Navigation map: all screens + transitions.

For mobile separately: behavior on interruption (call, notification), behavior on connection loss, orientation (portrait only, landscape only, both), Safe Area for iPhone with notch.

Monetization

Specific model with numbers: free-to-play + IAP, premium ($2.99 upfront), rewarded ads (target: eCPM $8–15 for casual). Description of each IAP: what we sell, pricing, where in the interface we offer it. Soft currency vs hard currency—sources (earning) and sinks (spending).

Energy mechanic if present: initial stock, regeneration time, maximum, ways to replenish. Specifically: 5 lives, regeneration 1 life/30 minutes, max 5, full regeneration 100 gems, 1 IAP of lives—20 gems.

Technical Requirements

Target platforms: iOS 15+, Android 8.0+. Engine: Unity 2023 LTS / Godot 4.x / Cocos Creator 3.x. Target FPS: 60 on iPhone 12+, 30+ on Android mid-range (Snapdragon 665+). Build size: up to 100 MB for first download (App Store / Play Store recommendations for cellular download). Asset streaming if needed.

Comparison of GDDs by Genre

Level of Detail

A GDD is a living document. You don't need to describe every particle before development starts. You do need to describe:

• Core mechanics — fully, down to numeric parameters
• First-hour experience — in detail
• Content plan (levels, chapters, events) — structure without details for each level
• Monetization — fully

Level design for specific levels goes into separate Level Design Documents (LDD) when you get to level creation.

Formats and Tools

GDD in Notion or Confluence — convenient for collaboration, versioning, comments. Alternative: Google Docs with table of contents. Diagrams: Miro or draw.io (FigJam). Balance tables: Google Sheets (not in GDD, but linked from GDD).

We don't write GDD in Word without version control — a month later no one knows which version is current.

What's Included in Our Work

• Concept interview (1–2 hours)
• Overview and concept document with references and moodboard
• Description of all core mechanics with diagrams and parameters
• UI/UX wireframes for key screens
• Navigation map of the app
• Monetization specification
• Technical requirements
• Content plan (levels, events, DLC)

Timeframes

3–5 working days — GDD for a hyper-casual or casual game. For a midcore/hardcore project with complex systems — 7–14 days. Cost is calculated individually.

We guarantee: after delivery, you receive a document ready to hand over to the development team. Contact us to discuss your project and order a GDD.

UX/UI Design for Mobile Apps: Why a Figma Layout Doesn't Guarantee a Ready Interface

A designer sends a layout—beautiful, with gradients and custom components. The developer opens it and realizes: the button is 36pt, the tap target is 20pt. On an iPhone SE, it's physically impossible to press with a thumb. The bottom sheet covers content when the keyboard appears. Navigation is built against the native iOS model. Apple will reject the app, or users will leave within a week—depending on how lucky you get with the review.

We have been designing mobile UX/UI for over 5 years and have seen hundreds of such situations. During this time, we have designed and helped launch 30+ mobile apps—from fintech products to social networks. You don't need to guess whether the design will pass App Review or Google Play—we embed platform requirements from the first screen. We'll assess your project in one day, contact us.

Mobile UX/UI is not an adaptation of web design. It is a separate discipline with specific platform constraints: safe area, touch gestures, UIViewController lifecycle, Activity state management.

Why Can't You Ignore Human Interface Guidelines and Material Design 3?

Apple HIG and Google Material Design 3 are not aesthetic recommendations. They are documented user expectations formed by years of using system applications. Expectations confirmed by user experience research on mobile platforms (User experience design).

HIG defines: minimum tap target 44×44 pt, safe area insets for notch and Dynamic Island, standard gestures (swipe back on iOS, back gesture on Android 10+). Ignoring safe area is a common mistake. safeAreaLayoutGuide in UIKit and safeAreaPadding in SwiftUI exist precisely for this. A designer who doesn't set safe area margins in Figma guarantees a bug during development.

Material Design 3 introduced Dynamic Color—the color scheme is generated from the user's wallpaper via MaterialTheme.colorScheme in Jetpack Compose. An app that ignores dynamic colors on Android 12+ looks out of place. This is not critical for niche products but is noticeable in mass-market apps.

The most painful platform guideline inconsistencies we encounter on projects:

• Custom navigation on top of system navigation. iOS users expect swipe back from any point on the left edge of the screen. A custom NavigationController without interactive gesture breaks this. Android users expect the system back button—a custom back button in the left corner does not fully replace it.
• Modal windows instead of navigation push. Bottom sheets are appropriate for actions, not for navigating content.
• Missing haptic feedback. UIImpactFeedbackGenerator on iOS is not decoration but part of the interface response. Buttons, swipes, and confirmation actions without tactile feedback feel broken.

Table: Comparison of iOS and Android UX/UI Requirements

How to Get the Most Out of Figma?

The Figma Variables API has changed the workflow. Design tokens—colors, typography, radii, spacing—are stored as variables and exported directly to code via figma-tokens or style-dictionary. This eliminates manual value transfer and desynchronization between design and implementation. Practice shows: Figma Variables speeds up asset handoff to development by 2–3 times compared to static frames, and using design tokens reduces code transfer errors by 60%.

Auto Layout with wrap and spacing between elements allows building components that behave like flex containers. A developer opens a component and sees not a static artifact but a description of behavior at different content sizes.

Component Properties—variants, boolean toggles, instance swaps—enable building a full design system right in Figma. A button with 4 states (default, hover, pressed, disabled), 3 sizes, and 2 icon variants is one component, not 24 frames.

Figma Prototype with Variables allows creating an interactive prototype with real state: showing how the screen changes with different variable values. This is no longer just a "clickable layout" but a full UX testing tool.

How to Benefit from Prototyping and UX Testing Before Development?

The most expensive mistake in a mobile product is to develop a feature, release it, and discover that users don't understand how it works. A Figma prototype at the testing stage costs zero development hours. Redoing a finished screen costs days. Testing a prototype before development begins reduces the number of fixes by 80%.

For usability testing, we use Maze (task testing on a prototype—the user goes through a scenario, we get heatmaps and mis-click rates) or direct sessions via UserTesting. Key metrics are task completion rate and time on task, not "like/dislike."

A/B testing on mobile is harder than on web: the App Store doesn't allow UI changes without an app update. Therefore, it's important to test hypotheses on a prototype before release, not through production experiments. According to research, fixing a bug found on a prototype costs 10 times less than after production release. And average task completion time increases by 40% after proper UX optimization during prototyping.

Why Are Animations Critical for Interface Perception?

Animations in mobile apps are feedback. An element doesn't appear instantly—it transitions to the desired state over 200–350 ms. This gives the brain context to understand what happened.

• iOS: withAnimation in SwiftUI, UIViewPropertyAnimator in UIKit for interactive animations with interruption capabilities. Spring animations with dampingRatio are the basis of most Apple system transitions.
• Android: AnimatedVisibility, animateContentSize, Crossfade in Compose. MotionLayout for complex scenes with multiple transformations.
• Flutter: AnimationController + Tween, Hero animations between screens, Lottie for After Effects exports. Lottie is especially effective for onboarding illustrations and empty states.

The key constraint is 16 ms per frame (60 fps) or 8 ms (120 fps on ProMotion devices). Animations must run on the GPU via CALayer/RenderThread, not on the CPU via layoutSubviews. Profiling via Core Animation instrument in Xcode is a mandatory step before releasing animated screens.

Why Is Accessibility Not an Optional Feature?

VoiceOver on iOS and TalkBack on Android are used by up to 15% of users—this statistic is confirmed by accessibility research described in Accessibility (Wikipedia). In absolute numbers for a large app, this is thousands of people. Additionally, App Store rejections due to accessibility occur, though rarely.

Minimum checklist:

• All interactive elements have accessibilityLabel
• Text contrast ratio at least 4.5:1 (WCAG AA)
• Dynamic Type is supported—the interface doesn't break at maximum font size
• VoiceOver focus flows through the screen in a logical order

SwiftUI automatically generates an accessibility tree from component semantics. UIKit requires manual setup of accessibilityTraits, accessibilityHint, and grouping via shouldGroupAccessibilityChildren.

What Does the Work Include?

The UX/UI design deliverables include:

What Is the Process and Timeline?

Design goes through stages: research and competitive analysis → user flows and wireframes → design system → UI layouts → prototype → testing → handoff to development.

Timeline estimates:

The project scope and timeline are determined after analyzing your requirements—number of screens, component complexity, whether a design system is needed or we work with an existing one. Get a consultation for your project—contact us for a preliminary assessment. Order a complete mobile app design—we'll assess your project in one day and propose the optimal work scope.