Building Video Games Without an Engine in 2025: A Practical Guide

If you want granular control over every aspect of your game in 2025—avoiding the complexity and unpredictability of major engines—building without Unity, Unreal, or Godot is a real option. This guide covers why developers are leaving big engines behind, what tools and libraries they actually use (according to current data), and the real trade-offs you’ll face if you go engine-less.

Key Takeaways:

• Engine-less development in 2025 offers unprecedented customization, deep technical learning, and performance gains—but expect much greater complexity and workload.
• Most devs use low-level libraries such as SDL2, GLFW, OpenGL, Vulkan, stb_image, and Box2D—not “do everything” engines.
• Engine-less workflows suit developers prioritizing control, transparency, and unique design over rapid prototyping or built-in tools.
• Main trade-offs: increased development time, limited portability, and a steeper learning curve.
• Commercial studios overwhelmingly favor engines for hiring and support. Engine-less is mostly for indies, hobbyists, and technical deep-dives.

Why Skip Engines in 2025?

Unity powers around 51% of all games released on Steam as of 2024. Unreal Engine accounts for 28%. Custom engines or raw-code builds make up less than 10% of the market, according to Klizos. So why do some developers still go engine-less?

• Total Creative Control: You have full authority over the look, feel, and internal systems of your game. As Noel Berry put it, “I am very particular about how my games feel and look, and how I interact with my tools” (OSnews).
• Performance Optimization: By skipping the engine, you avoid unnecessary bloat. You only include what you need, reducing binary size and memory usage—critical for mobile and browser-based games (Klizos).
• Avoiding Vendor Lock-in: Post-2023, many developers are wary of proprietary engines changing terms or breaking compatibility. When you write your own framework, you control your code and your distribution pipeline.
• Deep System Learning: Building your own loops, renderers, and systems means you understand memory, rendering, and real-time systems at a deeper level.
• Reduced Bloat: You skip the thousands of features you don’t need and focus only on what your game actually uses (Noel Berry).

This resurgence of raw-code game development is partly a reaction to recent industry events—especially licensing controversies and “black box” updates in major engines. For more on codebase transparency and ownership, see our analysis of AI code generation and provenance.

Toolkit for Engine-less Development

Engine-less doesn’t mean starting from zero. Developers assemble their own stack of low-level, purpose-built libraries. The following reflects the actual tools cited in current industry sources:

Notably, MonoGame is not cited in the 2025 engine-less workflow by any research source. The above libraries are favored for their minimalism and direct control (Klizos).

Sample Project Bootstrap (C++ with SDL2 and OpenGL)

To get started, you’d typically:

• Initialize a window and context with SDL2 or GLFW
• Set up your OpenGL or Vulkan renderer
• Write your own game loop
• Integrate libraries (e.g., stb_image for texture loading, Box2D for physics) as needed

For implementation details, refer to the respective libraries’ documentation:

• SDL2 Documentation
• GLFW Documentation
• OpenGL Documentation
• stb_image
• Box2D Documentation

Example: Loading an Image with stb_image.h

// Example: Load a PNG image using stb_image.h (C++)
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

int width, height, channels;
unsigned char* data = stbi_load("sprite.png", &width, &height, &channels, 0);
if (data) {
    // Upload data to GPU as a texture...
    stbi_image_free(data);
}
// This avoids engine asset pipelines—your format, your rules.

Understanding the Fundamentals

Building engine-less means you implement everything: the main loop, asset loading, rendering, and input. This offers complete transparency (and debuggability) but with far more responsibility. You’ll need a build system (like CMake or Cargo), version control (Git), and strong documentation from the start.

Step-by-Step: Building Blocks of a Game Without an Engine

Here are the essential systems you’ll need to create from scratch or via lightweight libraries:

1. Game Loop: Your main loop controls timing, updates, and rendering. This is the heart of your game’s architecture.
2. Direct Asset Loading: Use libraries like stb_image for images, bypassing any pre-baked engine pipelines.
3. Input Handling: SDL2 and GLFW provide cross-platform keyboard, mouse, and controller support.
4. Physics: Libraries like Box2D plug in for collision and movement, especially in 2D games.
5. Rendering: OpenGL or Vulkan give you direct access to GPU features, shaders, and optimizations.

Each of these systems can be swapped, replaced, or customized—no hidden magic, but also no guardrails.

1. Minimal Game Loop Example

// Pseudocode sketch for a basic SDL2-based game loop (C++)
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = SDL_CreateWindow("Game", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 800, 600, SDL_WINDOW_SHOWN);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);

bool running = true;
while (running) {
    SDL_Event event;
    while (SDL_PollEvent(&event)) {
        if (event.type == SDL_QUIT) running = false;
        // Handle input, etc.
    }
    // Update logic

    SDL_RenderClear(renderer);
    // Render your game
    SDL_RenderPresent(renderer);
}

SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();

This structure gives you full authority over update frequency, event handling, and rendering order.

2. Direct Asset Loading (stb_image)

// See previous stb_image.h example for asset loading
// Integrate as needed in your resource management code

3. Physics Integration (Box2D)

// Box2D initialization (C++)
b2Vec2 gravity(0.0f, -10.0f);
b2World world(gravity);

// Create a ground body
b2BodyDef groundBodyDef;
groundBodyDef.position.Set(0.0f, -10.0f);
b2Body* groundBody = world.CreateBody(&groundBodyDef);

b2PolygonShape groundBox;
groundBox.SetAsBox(50.0f, 10.0f);
groundBody->CreateFixture(&groundBox, 0.0f);

// Step the physics world
float32 timeStep = 1.0f / 60.0f;
int32 velocityIterations = 6;
int32 positionIterations = 2;
world.Step(timeStep, velocityIterations, positionIterations);

This gives you precise control over how physics and collisions work in your world.

Trade-offs and Alternatives

The choice to go engine-less carries significant implications. Here’s a direct comparison:

As both OSnews and Klizos highlight, most commercial studios standardize on engines for hiring and collaboration, while engine-less approaches are best suited to solo developers or those focused on mastering underlying technology.

Pitfalls and Pro Tips

• Underestimating Scope: Building even a minimal asset pipeline or debugging UI from scratch is a major undertaking. Focus on core gameplay first.
• Reinventing the Wheel: Use existing libraries for audio, images, and physics—don’t try to hand-roll everything.
• Cross-Platform Bugs: Major engines hide many OS- and hardware-specific quirks. Test on all target platforms early and often.
• No Editor by Default: Consider integrating a GUI toolkit like Dear ImGui for debugging and rapid iteration.
• Documentation Debt: As your project grows, thoroughly document all conventions, data formats, and workflows. This is critical if you ever scale up your team.

For lessons on homegrown automation and minimizing unnecessary complexity, see our analysis of decision trees in automation.

Conclusion & Next Steps

Making a video game without an engine in 2025 is not only possible—it can be rewarding for those seeking mastery, custom design, or freedom from vendor risk. You’ll gain deep system knowledge, but at the cost of speed and convenience. If you choose this path, start with a minimal loop, only add libraries you truly need, and document your architecture at every step.

Evaluate your project’s needs against the trade-offs above. For further insight, review our guidance on AI session management in code commits and terminal emulator performance for developers.

If you’re ready for the challenge, assemble your toolkit, open your editor, and build the game your way—down to the last byte.