There’s a moment in every game developer’s career where the thought strikes: “I should build my own engine.” For most, it remains a thought experiment. For some, it becomes an educational detour. For a rare few, it produces something genuinely useful.

Building a 2D game engine from scratch in 2026 is simultaneously more accessible and less necessary than ever before. The tooling is better, the resources are more abundant, and the existing options — from HGE to SDL to Raylib — cover most use cases. But there are legitimate reasons to do it, and understanding the architecture is valuable regardless of whether you ship your own engine.

Why Build Your Own?

Education

This is the strongest argument. Building an engine teaches you how games actually work at every level. Even if you never use your engine for a real game, the knowledge transfers to every engine you’ll ever work with.

As we covered in Getting Started with HGE, understanding what’s happening under the API calls — texture management, frame timing, input polling — makes you a more effective developer regardless of your chosen engine.

Specific Requirements

If your game has requirements that don’t fit existing engines well — a custom rendering pipeline, an unusual input scheme, a specific memory model — building the engine around those requirements can be more efficient than fighting against an engine’s assumptions.

Full Control

No black boxes, no mysterious bugs in code you can’t read, no dependency on another company’s release schedule. Everything is yours to understand, modify, and optimise.

The Joy of It

Some developers just enjoy systems programming. If building an engine is the part that excites you, and you’re realistic about the time investment, the enjoyment itself is a valid reason.

The Core Systems

Every 2D game engine, at minimum, needs these systems:

1. Window Management and Platform Layer

The foundation: creating a window, handling OS events, managing the application lifecycle.

Options:

  • SDL2: The standard choice. Cross-platform, well-documented, handles windowing, input, and audio
  • GLFW: Lighter weight, focused on window creation and OpenGL context management
  • Native APIs: Win32, Cocoa, X11 — maximum control, maximum platform-specific code

Start with SDL2 unless you have a specific reason not to. The abstraction cost is minimal and the portability is free.

2. Rendering Pipeline

For a 2D engine, the rendering pipeline converts sprite data into pixels on screen.

Immediate Mode: Each frame, iterate through visible sprites and issue draw calls. Simple, flexible, easy to debug. Can be slow if draw call count is high.

Batched Rendering: Accumulate sprite data into vertex buffers and issue fewer, larger draw calls. More complex but significantly faster for scenes with many sprites.

Texture Atlas: Pack multiple sprite images into single textures to minimise texture switching, which is one of the most expensive operations in 2D rendering.

HGE’s rendering approach — as documented in the sprite system and rendering functions — demonstrates a practical balance between performance and API simplicity that’s worth studying.

3. Input System

Abstract raw platform input (keyboard scan codes, mouse positions, gamepad axes) into game-meaningful actions:

Raw Input Layer → Action Mapping → Game Logic
  Key W pressed    → "move_up"      → player.moveUp()
  Left stick up    → "move_up"      → player.moveUp()

Key decisions:

  • Support rebinding from the start
  • Handle multiple simultaneous input devices
  • Distinguish between “pressed this frame” and “held down”
  • Dead zones and smoothing for analog inputs

4. Audio System

Game audio needs:

  • Sound effects: Short, triggered, potentially positional
  • Music: Long, streamed, with crossfading between tracks
  • Mixing: Multiple simultaneous sounds at controlled volumes

SDL_mixer, OpenAL, or miniaudio all provide solid foundations. The important part is your API design — game code should trigger “play explosion sound” without knowing about audio buffers and sample rates.

5. Resource Management

Load, cache, and unload game assets efficiently:

  • Lazy loading: Load resources when first requested, not at startup
  • Reference counting: Track usage and unload when no longer needed
  • Async loading: Load resources in a background thread to avoid frame hitches
  • File abstraction: Game code requests “player.png” without knowing whether it’s a loose file or packed in an archive

HGE’s resource management system provides a good model for how script-driven resource loading can simplify game code.

6. Game Loop

The heartbeat of the engine. Every frame:

  1. Process input
  2. Update game state (fixed timestep for physics, variable for rendering)
  3. Render the frame
  4. Present to screen

The fixed-timestep pattern is critical: game logic runs at a fixed rate (e.g., 60 updates per second) regardless of rendering framerate, with interpolation for smooth visual output between updates.

Architecture Decisions

Entity-Component-System (ECS) vs Object-Oriented

ECS: Entities are IDs. Components are pure data. Systems process components. Cache-friendly, great for many similar entities, steeper learning curve.

Object-Oriented: Game objects inherit from base classes, encapsulating behaviour. Intuitive, great for diverse entity types, can suffer from deep inheritance hierarchies.

Pragmatic approach: Start with a simple component model (objects with attached components) and evolve toward ECS if performance demands it. Most 2D games don’t have enough entities to need the cache benefits of pure ECS.

Scene Graph vs Flat List

Scene graph: Entities form a tree with parent-child relationships. Transformations cascade. Natural for UI and complex hierarchies.

Flat list: All entities in a single collection. Simpler, faster for iteration, harder to express hierarchical relationships.

For most 2D games, a flat list with optional parent references covers the need without scene graph complexity.

The Build System

Modern C++ projects need a build system that handles:

  • Cross-platform compilation
  • Dependency management (SDL2, image loading libs, audio libs)
  • Asset processing (texture packing, audio conversion)
  • Hot reloading during development (optional but valuable)

CMake is the standard for C++ projects in 2026. It’s not beautiful, but it works everywhere and has extensive documentation.

Using HGE as a Reference Architecture

If you’re building a 2D engine for educational purposes, studying HGE’s architecture is instructive:

  • The system state model shows how engine configuration can be clean and extensible
  • The callback-based game loop demonstrates one approach to the engine-game boundary
  • The blend mode system illustrates how to expose rendering control without exposing raw GPU state
  • The particle system demonstrates a complete subsystem from editor to runtime

As we discussed in HGE vs Modern Engines, HGE’s focused scope is part of its value as a reference — it demonstrates essential systems without the complexity of systems you don’t need.

When to Stop Building and Start Making a Game

The most dangerous trap in engine development is endless scope expansion. “I’ll just add physics. And networking. And a scripting language. And a level editor.”

Set a clear scope before you start:

  • Define the game you’re building the engine for
  • List the engine features that game requires
  • Build those features and nothing else
  • Use the game as the engine’s validation

An engine that powers one complete game is more valuable than an engine that has half-built support for everything.

What We’d Recommend

  1. Build an engine if you want to learn — it’s one of the best educational investments in game development
  2. Use an existing engine if you want to ship — unless your requirements genuinely don’t fit available options
  3. Study HGE and SDL as architectural references — they’re small enough to understand completely
  4. Start with rendering and input — these give you visible, interactive results immediately
  5. Build the game alongside the engine — don’t build engine features speculatively

The journey of building an engine is its own reward. But remember: the purpose of an engine is to enable a game. Don’t let the tooling become the project.

Explore engine architecture in practice through the HGE demos, or discuss engine development approaches in our community forum.