What Is a Game Engine? Bevy 0.20 and How Games Are Made

The short version: A game engine is a software framework built for making video games. It bundles the hard, reusable parts — a renderer, physics, audio, input, animation, and tools — so developers can focus on the game instead of reinventing the plumbing. Bevy is a free, open-source game engine written in Rust and built around the Entity Component System (ECS). Its 0.20 release, launched October 8, 2026, hit the front page of Hacker News thanks to a rewritten real-time path-tracing renderer called Solari. In this guide, we break down what is a game engine in plain English — what it is, how it works, and how to use it.

What Is A Game Engine: What does a game engine actually do?

Every video game needs to draw thousands of images per second, react to player input, play sounds, simulate gravity and collisions, and run smoothly across different hardware. Writing all of that from scratch for every game would be enormously wasteful, so engines package it once and let every game reuse it. A typical engine provides:

• Renderer: draws 2D sprites or 3D scenes using the graphics card.
• Physics engine: simulates gravity, collisions, and forces.
• Audio engine: loads, mixes, and positions sound effects and music.
• Input handling: reads keyboards, mice, touchscreens, and gamepads.
• Scripting: lets developers attach custom behavior to characters and objects.
• Animation and AI: moves characters and drives non-player opponents.
• Networking: synchronizes multiplayer games over the internet.
• Editor and tools: asset pipelines, debuggers, and profilers that speed up production.

Because the same engine is reused across many games, development gets cheaper and faster — and porting a game from PC to console or mobile becomes far more practical.

How do games get made with a game engine?

1. Pick the engine. Teams weigh the programming language, licensing, target platforms, and the kind of game they want to make. Switching engines mid-project is painful, so this choice matters.
2. Prototype the core loop. Build the smallest playable version — one mechanic, one level — to prove the game is fun before investing in art.
3. Create assets. Artists produce models, textures, sprites, sounds, and music, then import them through the engine’s asset pipeline.
4. Build systems and levels. Programmers wire up gameplay logic — movement, enemies, scoring, menus — while designers assemble the world.
5. Playtest and profile. Real players find the broken parts; profiling tools find the slow parts. This loop repeats until the game feels right.
6. Ship it. The engine compiles and packages the game for each target platform: PC, consoles, mobile, or the web.

What is Bevy?

Bevy is a refreshingly simple, data-driven game engine built in Rust — and it is free and open-source forever. That tagline comes from the project itself (bevy.org). It is dual-licensed under MIT and Apache 2.0, so anyone can use it for free, including for commercial games.

Bevy was first announced in August 2020 by its creator Carter Anderson and has been developed in the open ever since. Its design goals are explicit: capable (a complete 2D and 3D feature set), simple (easy for newbies, flexible for power users), data-focused (built on the Entity Component System), modular (use only what you need), fast (parallel where possible), and productive (quick compile times).

Two things make Bevy stand out. First, the language: Rust is known for memory safety without a garbage collector, a natural fit for performance-critical game code. Second, the workflow: rather than a giant visual editor, Bevy leans into a code-first approach where games are written in Rust.

What is the Entity Component System (ECS)?

ECS is the design pattern at the heart of Bevy, and it is simpler than it sounds. Instead of giant “Player” or “Enemy” objects containing everything, ECS splits game data into three ideas:

• Entities — plain IDs representing things in the world (a player, a bullet, a tree).
• Components — data attached to entities. In Bevy, components are just Rust structs: a Position, a Health, a Sprite.
• Systems — logic that runs over entities with certain components. In Bevy, systems are plain Rust functions, like “move everything with both a Position and a Velocity.”

Data laid out this way is fast for modern CPUs, and systems can run in parallel without tripping over each other — Bevy’s scheduler handles that automatically.

How is Bevy different from Unity, Unreal, and Godot?

Bevy’s biggest differences are its language and workflow. Unity and Godot developers spend much of their time in a visual editor; Bevy developers spend theirs in a code editor — a feature if you love Rust, a hurdle if you hoped to avoid programming. For a sense of how the “everything in code” idea plays out beyond games, see our piece on Remotion: Make Videos with React Code (2026 Guide).

Why is Bevy 0.20 trending?

Bevy 0.20.0 was released on October 8, 2026 (lib.rs crate history), and within days the release announcement reached the front page of Hacker News, climbing to roughly 250 points on front-page roundups for October 10–11 (HN roundup). That is unusual attention for a point release of a pre-1.0 engine.

The headline feature is Solari: a rewritten real-time path-tracing renderer, highlighted in community coverage of the release (GameFromScratch overview). Path tracing simulates how light rays bounce around a scene, producing more realistic lighting, shadows, and reflections than traditional rasterization — the same technique behind the “RTX” look in big-budget games. Bevy’s own feature list describes bevy_solari as providing “raytraced lighting (experimental)” (Bevy cargo features). The experimental label matters: this is cutting-edge tech being built in the open, not a finished product.

Is Bevy ready for real games?

Honest answer: it depends. Bevy’s own README warns the engine is still in early development, important features are missing, documentation is sparse, and new versions with breaking API changes ship roughly every three months (bevy.org). Migration guides are published each release, but upgrades are not always painless.

Still, people ship real projects with Bevy: indie games, game jams, simulations, even data visualizations. Bevy is strongest for Rust developers, for learners who want to see how engines actually work, and for hobby projects where breaking changes are acceptable.

How to start making a game with Bevy

1. Install Rust via rustup if you haven’t already.
2. Create a project with cargo new my_game and add bevy = "0.20" to your Cargo.toml.
3. Follow the official quick start on bevy.org — a minimal Bevy app is a few lines: create an App, add the default plugins, register a startup system, and run.
4. Work through the examples. Bevy ships hundreds of examples covering sprites, cameras, input, UI, and 3D scenes.
5. Pin your version. Because breaking releases arrive about every three months, pin the Bevy version and commit your Cargo.lock.

Learning Rust is part of the journey — the engine and the language come as a package deal. If you’re weighing languages, our overview of Python 3.15: What’s New and Why It Matters offers a useful contrast: Python optimizes for ease and readability, while Rust optimizes for safety and speed.

Frequently asked questions

Is Bevy free?

Yes. Bevy is free and open-source forever, dual-licensed under MIT and Apache 2.0. No fees, no royalties, no paid tiers — you can sell games made with Bevy without paying the engine anything.

What programming language does Bevy use?

Rust, entirely. Game logic, engine systems, and UI are all written in Rust, so expect to learn it alongside the engine.

Is Bevy good for beginners?

Bevy aims to be simple for newcomers and its code-first style means no complex editor to learn. But it is friendliest to people already comfortable with code, ideally Rust — absolute beginners may find Godot’s visual editor gentler.

What is Solari in Bevy?

Solari is Bevy’s experimental real-time ray-traced lighting system. Version 0.20 shipped a rewritten path-tracing renderer under this name, bringing cinematic-quality light, shadows, and reflections — still marked experimental, so expect rough edges.

Can Bevy make 3D games?

Yes. Bevy has 2D and 3D renderers with lights, shadows, cameras, meshes, materials, glTF model loading, and skeletal animation. A complete 2D and 3D feature set is one of the project’s stated design goals.

Do I need a game engine to make a game?

No — games can be built from scratch with raw graphics and audio libraries. But an engine handles the repetitive infrastructure (rendering, physics, input, asset loading) so you can spend your time on the game itself. If you build tooling around your project, practices like structured logging keep it debuggable — see What Is Observability? Logs, Metrics, Traces Explained.