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+# mrgameeng
+
+2D game engine built on MonoGame 3.8.4 (DesktopGL), .NET 8, C#.
+ECS-first: Friflo.Engine.ECS 3.6 is tightly integrated into the core — all gameplay
+state lives in components, all logic in systems.
+
+Design docs and developer documentation live in `docs/` and are written in **Russian**.
+Keep them up to date when architecture or conventions change.
+
+## Solution layout
+
+```
+src/      MrGameEng.* engine libraries (one per functional area)
+samples/  MrGameEng.Sample — demo game showcasing every engine feature
+tests/    xUnit test projects, one per engine library
+docs/     architecture, conventions, roadmap (Russian)
+```
+
+Engine modules: `Core` (game loop, ECS world, scenes, time), `Graphics` (custom batched
+renderer, camera, sprites), `Input`, `Audio`, `Assets` (runtime loading, no content
+pipeline), `Assets.Generator` (Roslyn source generator for typed asset handles).
+Dependency rule: every module may depend only on `Core`; `Core` depends only on
+MonoGame and Friflo.Engine.ECS. `Assets.Generator` is a netstandard2.0 analyzer.
+
+## Commands
+
+```
+dotnet build MrGameEng.sln
+dotnet test MrGameEng.sln
+dotnet run --project samples/MrGameEng.Sample
+```
+
+## Architecture rules
+
+- ECS-first: components are plain data (`struct` implementing `IComponent`),
+  behavior goes into Friflo systems (`QuerySystem`), wired through `SystemRoot`.
+  No `Update()` methods on game objects, no inheritance-based entities.
+- Hot paths (per-frame systems) must be allocation-free.
+- Rendering: custom batcher in `Graphics` (vertex buffers, layer→depth→texture sort,
+  atlas support); `SpriteBatch` is not used in engine code. Draw systems write vertices
+  directly from Friflo chunk iteration. Orthographic camera (one active per scene),
+  registered render layers (World or Screen space, optional Y-sort), AABB culling
+  against the camera rect before vertices are written.
+- No MGCB content pipeline. Assets are raw files under `Assets/`, loaded at runtime
+  (textures via `Texture2D.FromFile`, fonts via FontStashSharp, ogg via NVorbis,
+  shaders precompiled by `dotnet-mgfxc` at build time). Game code references assets
+  only through generated typed handles (`AssetRef<T>`), never string paths.
+- New engine functionality goes into the matching module, or a new
+  `MrGameEng.<Area>` library if it is a distinct area — never into `Core` by default.
+- Every public engine feature must be demonstrated in `MrGameEng.Sample`
+  and covered by tests where logic is testable without a GPU.
+
+## Code conventions
+
+- Nullable reference types enabled, warnings as errors, file-scoped namespaces.
+- Public engine API requires XML doc comments (English).
+- Tests: xUnit, named `Method_Scenario_Expectation`.