There’s a moment in every game developer’s career where the thought strikes: “I should build my own engine.” For most people, it stays 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 both easier and less necessary than it used to be. The tooling is better, the documentation is broader, and existing options - from HGE to SDL to Raylib - cover most day-to-day needs. That does not make the exercise pointless. There are still good reasons to do it, and the architecture is worth understanding even if you never ship your own engine.

Why people still build one

Education

This is the strongest argument, and the least flashy one. Building an engine shows you how games actually work under the hood. Even if the engine never powers a real project, the knowledge carries straight into every other engine you touch later.

As we covered in Getting Started with HGE, knowing what sits behind the API calls - texture management, frame timing, input polling - makes you a better developer whatever engine you end up using.

Specific requirements

Sometimes the game does not fit neatly inside someone else’s assumptions. A custom rendering pipeline, an unusual input scheme, a particular memory model - these are the sort of constraints that can make an off-the-shelf engine awkward rather than helpful.

At that point, building around the requirement can be cleaner than fighting the engine.

Full control

No black boxes. No mystery bugs in code you cannot read. No waiting on another company’s release schedule. If the whole stack is yours, you get to understand it, change it and tune it properly.

That is a real advantage, not a romantic one.

The simple pleasure of it

Some developers just like systems programming. Fair enough. If the work itself is the part that keeps you interested, and you are honest about the time it will take, that is a valid reason too.

The core systems every 2D engine needs

At minimum, a 2D engine needs a window and platform layer, a rendering pipeline, input, audio, resource management and a game loop. Leave one of those out and the whole thing starts leaning on something else to do the job.

1. Window management and the platform layer

This is the foundation: create a window, process OS events and manage the application’s lifecycle.

Options:

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

Unless there is a specific reason not to, start with SDL2. The abstraction cost is small and the portability is free.

2. Rendering pipeline

For a 2D engine, rendering is mostly about turning sprite data into pixels on screen. The trade-off is usually simplicity against draw-call count.

Immediate mode means each frame iterates through visible sprites and issues draw calls directly. It is simple, flexible and easy to debug. The catch is obvious: once the draw call count climbs, it gets slow.

Batched rendering collects sprite data into vertex buffers and sends fewer, larger draw calls. The code is more involved, but scenes with lots of sprites benefit from it.

Texture atlases pack multiple sprite images into a single texture, which cuts down texture switching - one of the more expensive things you can do in 2D rendering.

HGE’s rendering approach, as documented in the sprite system and rendering functions, is worth studying because it balances performance and API simplicity without pretending the problem is more complicated than it needs to be.

3. Input system

Raw platform input - keyboard scan codes, mouse positions, gamepad axes - should be abstracted into actions that make sense to the game.

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

A few decisions matter early. Support rebinding from the start. Handle multiple input devices at the same time. Distinguish between “pressed this frame” and “held down”. For analog inputs, dead zones and smoothing are not optional extras.

4. Audio system

Game audio needs three things at minimum: sound effects, music and mixing.

Sound effects are short, triggered and sometimes positional. Music is longer, usually streamed and often needs crossfading between tracks. Mixing is what lets multiple sounds play at once while keeping volume and priority under control.

SDL_mixer, OpenAL and miniaudio all provide solid foundations. The real work is in the API design. Game code should ask to “play explosion sound” without needing to know about buffers, sample rates or the rest of the plumbing.

5. Resource management

The engine needs to load, cache and unload assets without causing avoidable frame hitches.

Lazy loading keeps resources off the startup path until they are actually needed. Reference counting tracks usage and releases assets when nothing still points to them. Async loading moves work onto a background thread so the game does not hitch while a large texture or audio file comes in. File abstraction lets game code request “player.png” without caring whether it lives as a loose file or inside an archive.

HGE’s resource management system is a useful model here, especially if you want script-driven resource loading that keeps game code cleaner.

6. Game loop

This is the heartbeat of the engine. Every frame, the loop processes input, updates game state, renders the frame and presents it to the screen.

The fixed-timestep pattern matters. Game logic should run at a fixed rate - say, 60 updates per second - whether the renderer is hitting that rate or not. Rendering can stay variable, with interpolation filling the gaps so movement still looks smooth.

Architecture choices that shape the whole engine

ECS or object-oriented design?

ECS keeps entities as IDs, components as pure data and systems as the code that processes those components. It is cache-friendly and works well when there are lots of similar entities. It also has a steeper learning curve than people often admit.

Object-oriented design does the opposite. Game objects inherit from base classes and keep behaviour attached to the object itself. That is easier to reason about at first, and it suits games with more varied entity types. The drawback is familiar too: deep inheritance trees age badly.

The practical route is usually the least dramatic one. Start with a simple component model - objects with attached components - and move towards ECS only if the performance profile demands it. Most 2D games do not have enough entities to need pure ECS for cache reasons alone.

Scene graph or flat list?

A scene graph arranges entities as a tree with parent-child relationships, so transforms cascade naturally. That is a good fit for UI and more complex hierarchies.

A flat list keeps every entity in one collection. It is simpler, faster to iterate and less awkward to maintain, but it does not express hierarchy on its own.

For most 2D games, a flat list with optional parent references is enough. Scene graph complexity is easy to justify and hard to remove later.

The build system side of the job

Modern C++ projects need a build system that handles cross-platform compilation, dependency management, asset processing and, if you want it, hot reloading during development.

That means SDL2, image loading libraries and audio libraries need to fit cleanly into the build. Texture packing and audio conversion should sit somewhere sensible too. Hot reloading is optional, but it is useful once the project starts growing.

CMake is the standard for C++ projects in 2026. It is not beautiful. It does work everywhere, though, and the documentation is extensive enough that you can usually get unstuck without much drama.

HGE as a reference architecture

If the goal is educational, HGE’s architecture is worth studying closely. Its architecture is small enough to understand as a whole, which is rare once engines accumulate subsystems beyond their original scope.

The system state model shows how engine configuration can stay clean and extensible. The callback-based game loop shows one way to define the engine-game boundary. The blend mode system shows how to expose rendering control without handing raw GPU state to every caller. The particle system is another useful example because it demonstrates a complete subsystem from editor to runtime.

As we discussed in HGE vs Modern Engines, HGE’s focused scope is part of the point. It shows the essential systems without burying them under features you may never use.

Knowing when to stop

The most dangerous trap in engine work is scope creep dressed up as ambition. “I’ll just add physics. And networking. And a scripting language. And a level editor.” That road has a familiar destination, and it is usually not a finished game.

Set the scope before you start. Define the game the engine is for. List the features that game actually requires. Build those features and leave the rest alone. Use the game as the engine’s validation, not as a thing you might get to after the engine is done.

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

A sensible way to approach it

Build an engine if the goal is learning. It is one of the better educational investments in game development.

Use an existing engine if the goal is shipping, unless the requirements really do not fit the available options. Study HGE and SDL as architectural references because they are small enough to understand completely. Start with rendering and input so you get something visible and interactive early. Build the game alongside the engine instead of inventing features speculatively.

The work is its own reward, but the purpose of an engine is still to enable a game. Do not let the tooling become the project.

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