Building an endless runner with Phaser teaches core game development skills while producing a compact, playable project that demonstrates physics, procedural content, and deployment workflows.
Key Takeaways
- Project foundation: Use a clear project structure, Node.js, and a bundler like Vite or webpack to streamline development and deployment.
- Core systems: Implement the main scene with Arcade Physics, object pooling, and a distance-based spawn scheduler for deterministic behavior.
- Game feel: Tune jump math, hitboxes, and polish (particles, camera shake, audio variance) to create satisfying feedback.
- Performance & devices: Optimize draw calls with atlases, reuse objects to avoid GC spikes, and test on mobile browsers for responsiveness.
- Security & fairness: Treat client-reported scores as untrusted for global leaderboards and validate important logic on the server.
- Iterate with data: Use analytics ethically, playtest often, and adapt difficulty gradually based on player performance metrics.
Project setup — tools, structure, and first scene
Before writing code, the developer should select tools that match the project’s goals and timeline. For Phaser 3 projects, a typical modern stack includes Node.js for package management, a fast bundler such as Vite or a mature tool like webpack for builds, and a local static server or the bundler’s dev server for testing. Node.js is available at nodejs.org, and Vite documentation is at vitejs.dev.
Project layout matters for maintainability and team collaboration. A practical structure is:
- index.html — main HTML shell and canvas container.
- /src — JavaScript or TypeScript source files, split into scenes, components, and utilities.
- /assets — images, audio, JSON data and tilemaps.
- /dist or /build — production build output for deployment.
- package.json — scripts, dependencies, and metadata.
- /tests — optional unit and integration tests for non-visual logic.
To bootstrap quickly, the developer can run commands such as npm init -y, npm install phaser, and npm install –save-dev vite. Committing early to a Git repository enables collaboration and effortless hosting on services like GitHub Pages, Netlify, or Vercel.
When creating the first scene, it is helpful to keep it minimal. The developer should implement a boot or preload scene to load assets and an initial game scene that creates a background, player sprite, and a ground. A typical Phaser configuration might appear as an object with properties type, width, height, physics (default ‘arcade’), and scene array that lists BootScene, GameScene, and UIScene. Using Arcade Physics is often the best choice for an endless runner because it is lightweight and predictable.
Starter patterns and code organization
Early decisions about code organization save time later. The developer should separate code into clear responsibilities: scenes manage lifecycle, player and obstacle classes encapsulate behavior, and utility modules handle config and shared math. This structure enables easier testing and reuse.
- Scene files — BootScene for loading, GameScene for core loop, UIScene for HUD and menus.
- Prefabs / classes — Player, Obstacle, Collectible classes that extend Phaser game objects or wrap them.
- Managers — SpawnManager, AudioManager, PoolManager to centralize non-visual logic.
- Config — A single source of truth for tunable values like baseSpeed, gravity, and UI layout.
Example flow: BootScene loads assets and then starts GameScene. GameScene calls initPlayer(), initPools(), initInput(), and starts the spawn scheduler. Each method should be short and testable. Using ES modules or TypeScript helps enforce boundaries and improves maintainability.
Assets and art pipeline
Art choices directly affect readability and performance. For rapid prototyping, simple vector shapes or free sprite packs are sufficient; as the project matures, the developer can move to texture atlases and optimized sprites. Organizing assets by layer—foreground obstacles, midground platforms, background parallax, and UI—keeps the pipeline clear.
Key asset considerations:
- Sprite sheets consolidate frames and reduce draw calls; Phaser supports JSON atlases via scene.load.atlas(‘key’, ‘image.png’, ‘data.json’).
- Texture atlases minimize texture switches and improve batching; tools like TexturePacker or the free Shoebox workflow can be used.
- Audio should use compressed formats (OGG/MP3) with short loops for background and small effects; Web Audio APIs perform better with decoded buffers for repeated sounds.
- Placeholder art accelerates iteration: lock core mechanics first, then polish visuals.
Phaser’s loader allows multiple formats such as images, atlases, tilemaps, and audio. The developer should implement a loading screen that reports progress and gracefully handles failed loads. For large assets not needed at startup, use lazy loading in later scenes or on demand to reduce initial load times.
Core game loop and scene design
An endless runner typically separates gameplay into a single main scene and supporting scenes for UI and menus. The main scene handles input, procedural spawning, world scrolling, collisions, scoring, and difficulty state. Breaking logic into methods such as initPlayer(), initObstacles(), updateDifficulty() keeps update() focused on per-frame state changes.
Phaser’s lifecycle methods—init(), preload(), create(), update(time, delta)—map naturally to game phases. The developer should use the time and delta parameters for deterministic movement: velocity = speed * (delta / 1000) yields frame-rate independent motion. Where possible, use timers and events for scheduled actions rather than heavy per-frame logic.
Player controller and jump math
Player motion defines much of the feel in an endless runner. Whether the player can only jump, double-jump, dash, or slide, the controller should be responsive and predictable. The developer should model vertical motion with basic kinematics to tune jump height and duration.
Practical jump tuning approach:
- Decide the desired jump apex height and time to apex in seconds. From physics, gravity = 2 * apexHeight / (timeToApex^2) and initialVelocity = gravity * timeToApex.
- Use Arcade Physics gravity and set the player’s initial vertical velocity to -initialVelocity on jump (negative because Y increases downward in Phaser).
- Optionally change gravity while the player is ascending vs descending to create snappier or floaty jumps (in Arcade, this can be approximated by applying additional velocity modification in update()).
For a double-jump, grant a second jump only if the double-jump flag is set and reset it on landing. For dashes, temporarily override horizontal motion with a velocity spike and ignore gravity changes for that brief window if desired. Input buffering helps remove borderline missed jumps: store the last input timestamp and accept it if the player lands within a small buffer window (100–200 ms).
Physics fundamentals for an endless runner
Phaser offers both Arcade Physics and Matter.js. Arcade is efficient and suitable for axis-aligned bounding box logic. Matter.js provides rigid-body physics with more accurate collisions and constraints but adds complexity and performance cost. The developer should choose Arcade for most runners unless physics-based puzzles or complex shapes demand Matter.
Arcade Physics basics to tune:
- Gravity — controls fall speed; tuned as described in jump math.
- Velocity — horizontal velocity is often implemented by moving obstacles; keep player horizontal velocity stable if the player is mostly vertical-moving.
- Drag and acceleration — useful for slippery or momentum-based mechanics.
- Immovable bodies — obstacles set with body.immovable = true so the player does not push them.
For world motion, the two common approaches are moving obstacles leftward or moving the camera rightward across the map. Moving obstacles is simpler for endless procedural generation. Moving the camera with tile-based levels suits more structured tracks and when parallax layers must align with camera position.
Collision detection and response
Collision fairness is critical. Phaser Arcade Physics supports physics.add.collider for solid collisions and physics.add.overlap for collectible triggers. The developer should decide the game’s reaction to collisions—immediate game over, health reduction, knockback, or temporary invulnerability—and implement clear feedback for each choice.
Good collision handling practices:
- Use groups to organize game objects: obstaclesGroup, coinsGroup, enemiesGroup.
- Attach colliders and overlap callbacks explicitly: scene.physics.add.collider(player, obstaclesGroup, onPlayerHit, null, this).
- Implement an invulnerable flag to ignore repeated collisions during recovery and show visual cues like blinking.
- Tune hitboxes using setBodySize(width, height) and setOffset(x, y) to make collisions feel fair and avoid pixel-perfect surprises.
If irregular shapes are required, the developer can switch to Matter.js or approximate shapes with multiple Arcade bodies or sensor zones. For many runners, a slightly forgiving rectangle hitbox is preferable for better player experience.
Obstacle generation, pooling, and spawn scheduling
Efficient obstacle generation relies on object pooling and a spawn scheduler that is independent of frame rate. Constantly creating and destroying sprites leads to garbage collection spikes; pooling allows reuse. Phaser groups offer convenient pool management via getFirstDead() or get() in newer versions.
Patterns to implement:
- Prefab templates — maintain a small set of obstacle templates with metadata such as width, safeGap, and cleanupMargin.
- Object pooling — pre-create N instances per type and reactivate them with new positions and states when needed.
- Distance-based spawning — track runDistance += worldSpeed * (delta / 1000) and spawn when runDistance – lastSpawnDistance >= spawnInterval to keep spawn behavior consistent across frame rates.
- Validation rules — after generating a candidate spawn, validate it against rules such as minimum gap, maximum slope, and no overlap with active hazards.
An effective spawn scheduler uses a combination of timers and distance counters. The developer can randomize spawn intervals within a bounded range and adapt them to difficulty. Logging spawn events during playtests helps identify patterns that cause unfair deaths.
Difficulty ramp and balancing
A well-designed ramp keeps players challenged without overwhelming them. The developer should plan how difficulty changes over time via world speed, spawn frequency, obstacle complexity, and new enemy behaviors. The ramp must be smooth, testable, and reversible if it becomes too punishing.
Balancing tips:
- Parameterize everything — expose baseSpeed, speedGrowth, baseSpawnInterval, and minGap so these can be tuned without changing code logic.
- Performance-based adjustments — increase difficulty slowly based on elapsed time or distance, not frame count.
- Adaptive difficulty — collect simple metrics like average run length and deaths per minute; nudge parameters for players who struggle or soar.
- Playtest with a cohort — gather session recordings or telemetry to understand real player behavior and outlier failure cases.
Example formula: worldSpeed = baseSpeed + speedGrowth * Math.min(elapsedSeconds, speedCapTime). Ensure caps for speed and minimum spawn intervals to prevent impossible states. The developer should also include “soft gates”—periods where new obstacle types are introduced slowly with clear telegraphing so players can learn.
Polishing collisions and game feel
Game feel shapes perception. Small feedback systems—screen shake, particle effects, sound pitch modulation, and animation speed changes—make actions and collisions feel satisfying. The developer should treat these as tunable systems rather than hard-coded effects.
Concrete polishing ideas:
- Camera shake — use small camera offsets for a brief duration on significant events such as death or big landings.
- Particles — emit small particles on footsteps, landings, and obstacle destruction.
- Audio variance — slightly randomize pitch and volume of repeated sound effects to avoid fatigue.
- Animation blending — speed up running animations as world speed increases to visually communicate momentum.
Implementing invincibility frames can be achieved by toggling collisions off for a short period and animating the player sprite’s alpha or tint. Provide clear audio cues when invincibility starts and ends to avoid ambiguity.
Controls, input handling, and accessibility
Controls must be tight and accessible across platforms. The developer should support keyboard, touch, mouse, and gamepad input. Phaser simplifies this with scene.input and scene.input.keyboard APIs. Gesture handling for swipes can be implemented with pointer events and simple threshold checks.
Control schemes to consider:
- Taps / clicks — often map to jump; double-tap can map to double-jump or dash.
- Hold to charge — press and hold to prepare a longer jump or perform a charged ability.
- Swipes — upward swipe to jump, downward swipe to slide; this requires velocity and direction checks.
- Gamepad support — poll gamepad axes and buttons and map to actions for TV or controller-based experiences.
Accessibility is often overlooked but increases audience size. The developer should include colorblind-safe palettes, configurable audio levels, remappable controls, and visual alternatives to sound cues. For text accessibility, ensure fonts scale and the HUD is readable on small screens.
UI, scoring, persistence, and progression
The HUD should present essential data: current score, best score, health or lives, and active power-ups. A separate UIScene is an effective pattern that renders UI on top of the GameScene and persists between retries or level transitions.
Scoring and persistence options:
- Distance-based scoring — score increases with distance traveled and is deterministic.
- Collectibles — coins or pickups add to score or currency used for unlocks.
- Local persistence — window.localStorage is appropriate for single-player high scores and settings: localStorage.setItem(‘best’, score).
- Global leaderboards — require a backend and secure submission to prevent cheating; server-side validation or replay verification increases trust.
Progression systems that improve retention include unlockable characters, cosmetic skins, daily challenges, and gradual power-up introductions. Each progression element should be carefully balanced so it rewards play without creating pay-to-win situations if monetization is introduced.
Analytics, privacy, and ethical telemetry
Collecting analytics enables data-driven tuning. Useful events include session start/end, death reason, distance at death, and user flow through menus. The developer should be mindful of privacy laws—implement consent flows when required and avoid collecting personally identifiable information without clear justification.
Best practices:
- Prefer aggregated, anonymized metrics for tuning difficulty and feature engagement.
- Use reputable analytics platforms like Google Analytics or open-source solutions; follow their privacy guidelines.
- Implement a user-facing privacy policy when collecting data beyond ephemeral gameplay metrics.
Testing, debugging, and continuous integration
Robust testing practices reduce regressions and improve confidence when iterating. While automated visual tests for games are challenging, many parts of game logic are unit-testable: spawn rules, difficulty curves, and score calculations.
Testing strategies:
- Unit tests for deterministic logic such as spawn schedule calculators and difficulty functions using frameworks like Jest or Mocha.
- Integration tests for systems that can be exercised headless—object pooling, serialization, or leaderboard APIs.
- Manual playtests with checklists that cover collision edges, input timing, and mobile performance.
- Profiling using browser devtools and Lighthouse to find bottlenecks in rendering and loading.
For continuous integration, simple pipelines can run build checks and unit tests via GitHub Actions, GitLab CI, or similar. A sample GitHub Actions workflow might run npm install, run lint and tests, and build the production bundle on push to a release branch. Deployments to Netlify or Vercel can be automated by connecting the repository and setting up branch-specific rules.
Performance optimizations for web and mobile
Performance is critical, especially for mobile browsers with limited CPU and memory. The developer should profile early and adopt patterns that avoid heavy frame-time work.
Optimization checklist:
- Texture atlases and sprite sheets to reduce draw calls.
- Object pooling to minimize memory churn and GC pauses.
- Deactivate off-screen objects and reduce physics bodies when objects are far off-camera.
- Limit particle systems and consider reducing particles on low-end devices.
- Responsive assets — serve appropriate resolutions per device; use srcset-like strategies for images where suitable.
- Compression — enable gzip or Brotli for JS bundles and serve optimized image formats (WebP where supported).
Lazy-load large assets (music tracks, high-resolution backgrounds) and provide immediate interactive experiences with placeholders while the rest loads. Use the browser’s performance profiling tools to identify long-running scripts or paint-heavy frames.
Mobile-specific considerations
Mobile controls, orientation, and browser limitations require careful handling. The developer should test on both iOS and Android browsers and consider PWA support for home-screen installation.
Mobile tips:
- Touch target sizes — ensure on-screen buttons are large enough to tap comfortably.
- Orientation support — prefer a single orientation (landscape or portrait) and provide a clear orientation lock or prompt.
- Battery and CPU — reduce update frequency for background tabs and lower graphics fidelity when battery saver modes are detected.
- PWA — add web app manifest and service worker to allow offline play and faster load on repeat visits.
Security, anti-cheat, and leaderboard integrity
Client-side games are vulnerable to tampering. If the game includes leaderboards or currency, the developer must treat any client-reported data as untrusted. Server-side verification prevents the most direct cheating vectors.
Security recommendations:
- Validate scores server-side where feasible, using replay validation or deterministic server checks.
- Rate-limit and authenticate leaderboard endpoints to prevent spam and scripted submissions.
- Use HTTPS to protect API traffic and ensure CORS headers allow only intended origins.
- Obfuscation of client code is not a security solution but may raise the effort required for casual cheaters.
For many indie projects, a pragmatic approach is to start with local leaderboards and add server-side validation only when global competition becomes a priority.
Monetization models and user experience
If monetization is planned, the developer should choose models that align with player expectations and maintain fairness. Common approaches include ads, cosmetic in-app purchases, and optional one-time purchases to remove ads.
Monetization principles:
- Non-intrusive ads — rewarded ads that grant in-game currency or retries are often better received than forced interstitials.
- Cosmetic purchases — skins and characters that do not affect balance maintain fairness.
- Paywall avoidance — avoid gating core progression behind paywalls; players expect skill to matter most in endless runners.
- Transparency — clearly communicate what purchases do and avoid deceptive practices.
Any analytics and purchase flows should comply with local regulations (e.g., consumer protection and data privacy laws). If targeting minors, implement additional safeguards and parental consent where mandated.
Extending the game — advanced features and directions
Once the core is stable, the developer can plan expansions that add depth without undermining fairness:
- New obstacle behaviors — moving platforms, rotating barriers, and teleporters that require reading patterns.
- Power-ups — temporary shields, magnets for collectibles, or slow-motion effects that change gameplay dynamics.
- Character abilities — unique mechanics per character to encourage experimentation and replay.
- Theme progression — procedurally or conditionally switching visual themes and music to reinforce a sense of distance traveled.
- Local multiplayer — split-screen or asynchronous leaderboards that encourage social play.
Each new system should be prototyped with the same discipline as the core: isolate it, test it, and measure its impact on retention and difficulty.
Advanced physics: when to choose Matter.js
If the game requires realistic rigid-body interactions, constraints, or compound shapes, Matter.js is a strong option. It supports convex hulls, constraints, and complex collision filtering, which can be useful for physics puzzles or destructible environments.
Consider Matter when:
- Obstacle interactions require rotation, torque, or realistic stacking.
- Collision shapes need concave polygons or compound bodies.
- Constraints and joints are part of gameplay mechanics.
Keep in mind Matter adds CPU cost and complexity. The developer should profile and limit active bodies, and consider hybrid approaches—Arcade for most gameplay and Matter for specific scenes—if appropriate.
Recommended learning resources and community practices
To build competence, the developer should combine official documentation, community examples, and hands-on experimentation. Useful resources include:
Exploring open-source Phaser projects on GitHub and reading community articles accelerates learning. The developer should clone small projects and instrument them to see how pros handle pooling, audio, and performance.
Troubleshooting common issues
Certain problems recur in endless runner projects. Here are targeted remedies:
- Collision misalignment — enable Arcade debug (arcade.debug = true) during development to visualize bodies and adjust setBodySize and setOffset accordingly.
- Impossible gaps — tighten spawn validation rules and adjust minGap based on current worldSpeed and player capabilities.
- Mobile performance dips — profile draw calls, reduce active particle systems, and lower texture sizes for mobile builds.
- Assets not loading after deploy — check relative paths, case sensitivity on servers, MIME types, and whether the bundler has fingerprinted filenames that the HTML doesn’t reference.
- Audio latency on mobile — pre-decode audio buffers or use short OGGs and ensure user interaction has unlocked Web Audio contexts.
Iterative testing—play, note problems, apply small fixes, and repeat—produces the best results. Developers should also gather player feedback early to surface discoverability and control clarity issues.
Checklist before public release
Before releasing the game publicly, the developer should run through a release checklist:
- Verify builds for target browsers and devices using automated and manual tests.
- Confirm that assets are compressed, and the bundle size is acceptable for expected network conditions.
- Validate analytics and privacy flows, and ensure any required consent banners are in place.
- Test monetization flows, refunds, and in-app purchase receipts where applicable.
- Ensure leaderboards or servers are secured and rate-limited.
- Prepare marketing assets and social metadata (Open Graph tags) for sharing the game link.
Publishing incrementally—soft launch to a small audience—helps validate assumptions and identify critical issues before scaling up.
Which mechanic will the developer prototype first: a double-jump, a dash, or moving obstacles? Trying one mechanic at a time and measuring its effect on difficulty and player enjoyment is the most efficient approach.
