Architect Your First Game: Loop, State, Collisions

The game loop is the heartbeat of every playable experience, providing structure and rhythm from start to finish. This guide charts a practical, step-by-step route to building a minimal, reliable game architecture. You'll learn to implement key systems—from input and physics to sound and packaging—enabling you to craft a controllable entity, handle collisions, sustain a smooth frame rate, and easily share your project with others.

Launching your game project begins with a systematic approach: you'll construct a main loop to drive updates, manage state for predictable behavior, capture and process user input, calculate physics and collisions, render graphics for clear visuals, sync audio effects, enable save/load persistence, and finally, wrap everything for distribution.

By following this foundation, you'll gain a working prototype with a responsive entity, simple collision detection, stable performance, and effortless packaging for others to play.

Keywords: Guide To Build Your Own Game, game loop, state management, collision detection, physics engine, game input, rendering, audio, save/load, packaging systems

Prerequisites & Setup by Environment

JavaScript Canvas

Tool: Any modern browser, Visual Studio Code, Node.js (optional)
Steps: Create a new folder, add index.html and main.js. Link your script in HTML.
Main Loop Placement: Place main loop in main.js, called via requestAnimationFrame.

Unity C#

Tool: Unity Editor (recommended version 2022+)
Steps: File > New Project, select 2D or 3D.
Main Loop Placement: Use Update() or FixedUpdate() in a MonoBehaviour script.

Godot GDScript

Tool: Godot Engine (version 4.0+)
Steps: Start new project, select 2D or 3D scene.
Main Loop Placement: Place main loop logic in _process or _physics_process methods.

Main Loop: Fixed vs Variable Timestep

Fixed Timestep

 while (running) { accumulator += deltaTime; while (accumulator >= fixedStep) { update(fixedStep); accumulator -= fixedStep; } render(); }

Choose this if you want consistent physics and predictable gameplay across all devices.

Variable Timestep

 while (running) { update(deltaTime); render(); }

Choose this if you prioritize maximum frame rate and responsiveness, but accept physics variance.

Performance Budget

Budget Item	Target	Quick Check
Draw Calls	< 50/frame	Profiler: Count per frame
Texture Size	< 2MB	Inspect asset folders
Update Time	< 8ms/update	Profiler: Frame time

Collision Recipes

AABB (Axis-Aligned Bounding Box):
- Formula: If (boxA.x < boxB.x + boxB.width) and (boxA.x + boxA.width > boxB.x) and (boxA.y < boxB.y + boxB.height) and (boxA.y + boxA.height > boxB.y) then collision.
- Tip: Watch for off-by-one errors—false positives can occur if edges just touch.
Circle vs Circle:
- Formula: Distance between centers < sum of radii = collision.
- Tip: Use squared distances to avoid unnecessary square root calculations; false negatives if radii are miscalculated.
Tilemap Solids:
- Steps: Convert entity position to tile index; check tile property for solidity.
- Tip: Be careful with rounding positions—false positives if entity is exactly on the edge between tiles.

State Management & Input

Keep game states (menu, play, pause) in a central controller or simple enum.
Capture input events (keyboard, touch, controller) and update entity velocity or actions accordingly.
Verify: When pressing input, the entity responds and moves on screen.

Physics & Collisions

Apply velocity and acceleration to entities each update.
Run collision recipes, adjusting position or velocity on impact.
Verify: Entities stop, bounce, or react when colliding with boundaries or other objects.

Rendering

Draw backgrounds, entities, and UI in correct order each frame.
Optimize for minimal draw calls and clear visuals.
Verify: Entity and UI visuals update smoothly and accurately with user actions.

Audio

Play sound effects for actions (like jump, collision, win) and background music.
Sync sounds to events for responsive feedback.
Verify: Audio plays at the correct moments and does not overlap unexpectedly.

Save/Load

Store game state (score, level, settings) via local storage or files.
Load state on startup or resume, confirming restoration of progress.
Verify: Saved progress reloads correctly after restarting the game.

Packaging

Export your project for platforms (web, desktop, mobile) using built-in tools.
Test package on target device to ensure compatibility and performance.
Verify: Game starts and runs correctly from packaged file or installation.

Common Errors Clinic

Input Stutter

Symptom — Entity jitters or pauses randomly
Likely Cause — Multiple input handlers or frame drops
Fix — Debounce input events, optimize loop timing.

DeltaTime Spikes

Symptom — Sudden fast or slow entity movement
Likely Cause — Background tasks or tab switching
Fix — Clamp deltaTime to sensible values, avoid processing huge time gaps.

Asset Loading Races

Symptom — Missing textures or sounds during gameplay
Likely Cause — Assets not fully loaded before start
Fix — Preload all assets and confirm readiness before entering main loop.

Quick FAQ

How can I keep my game running smoothly?
Monitor your performance budget and use fixed timestep for logic updates.
What is the fastest way to prototype a simple entity?
Focus on input, physics, and a basic render loop before adding advanced features.
Which is the most important collision method for beginners?
AABB collision works well for most starter projects due to its simplicity and reliability.

References

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