HL2-Style Engine (C# / Veldrid)

A custom C# game engine inspired by Half-Life 2–style architecture, built from the ground up using .NET 8, Veldrid, and ImGui, with a strong focus on clean separation between engine and game code, fast iteration, and long-term scalability.

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✨ Features

• Custom engine architecture (no Unity / Unreal)
• Clear separation between Engine and Game
• Cross-API rendering via Veldrid
• Immediate-mode debug UI with ImGui
• FPS-style camera and movement foundations
• Fixed-timestep simulation loop
• SDL2 windowing and input
• Designed for fast compile times
• Editor-friendly, iteration-focused structure

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📄 Overview

This project explores how FPS-style engines are structured internally, inspired by classic Source-engine concepts but implemented using modern C# and .NET.

Key goals:

• No engine–game coupling
  Games consume engine APIs they never modify engine internals.
• Fast iteration
  Small rebuilds, minimal recompiles, clear module boundaries.
• Explicit systems
  Rendering, input, movement, timing, and UI are explicit systems.
• Editor-ready foundations
  Designed to support in-game editing and tooling later.

This is a learning project.

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🧱 Architecture

The solution is split into clearly defined projects:

Engine.Core      → Math, time, shared utilities
Engine.Platform  → Windowing, input, OS abstraction
Engine.Render    → Rendering, shaders, GPU resources
Engine.Runtime   → Engine host, main loop, lifecycle
Game             → Game-specific code (uses engine APIs)

🎮 Runtime Flow

High-level execution flow:

1. Engine creates window and graphics device
2. Game module is initialized
3. Main loop:
   • Pump OS events
   • Update input
   • Per-frame update
   • Fixed-timestep simulation
   • Render world
   • Render ImGui debug UI
4. Clean shutdown and disposal

This mirrors how professional engines structure their runtime.

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🖥 Rendering

• Backend-agnostic rendering via Veldrid
• Currently targeting Direct3D11 (Windows)
• Explicit command lists and pipelines
• World rendering and ImGui rendering are separated

Designed to expand into:

• Depth buffering
• Multiple render passes
• Debug overlays
• Editor gizmos

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🧭 Input & Camera

• SDL2-based input
• Relative mouse input for FPS camera
• Source-inspired movement foundations
• Fixed-timestep movement simulation
• Camera cleanly decoupled from rendering

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📦 Requirements

• Windows
• .NET SDK 8.0+
• Visual Studio 2022 (recommended)

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🚀 Getting Started

1. Clone the repository
2. Open the solution in Visual Studio 2022
3. Restore NuGet packages
4. Set Game as the startup project
5. Build and run

The engine will launch a window with a basic world and debug UI.

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🛠 Current Status

Actively developed

Implemented:

• Engine / game separation
• Windowing & input
• Rendering pipeline
• ImGui integration
• FPS camera & movement base

Planned:

• Depth buffer & resize handling
• Basic level geometry
• In-game editor tools
• Scene serialization
• Hot-reloadable content
• Asset pipeline

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📌 Motivation

This project exists to:

• Deepen understanding of real engine architecture
• Avoid black-box engines
• Build reusable, testable systems
• Demonstrate low-level engine knowledge for portfolio and interviews