Cthulhu is a custom 3D game engine written in C++ for building first-person shooter games.

The long-term goal is to create a serious, editor-driven FPS engine with a focused scope rather than a general-purpose engine.
Early visual targets are inspired by Return to Castle Wolfenstein and Serious Sam, with room to grow into more advanced rendering over time.

• Build a dedicated FPS-focused engine
• Use OpenGL for rendering
• Create a full editor workflow
• Support glTF assets
• Add Lua scripting later
• Integrate Jolt Physics for world simulation
• Keep the engine narrow in scope and purpose-built

Cthulhu is in early development.

• Engine static library with SandboxSample game project
• Engine application wrapper with update callbacks
• Window & input system (GLFW + GLAD, OpenGL 3.3)
• glTF/GLB model loading with materials and embedded textures
• Renderer pipeline (shadows → main pass → grid → skybox → ImGui)
• Blinn-Phong lighting with directional and point lights
• Shadow mapping (2048x2048, PCF)
• Frustum culling (AABB-based)
• HDR skybox with equirectangular-to-cubemap conversion
• HDR tonemapping and gamma correction
• Scene system with JSON scene files
• Jolt Physics integration (static & dynamic bodies, ground plane)
• FPS Character Controller (capsule collision, gravity, jumping)
• Editor/Game mode toggle
• Fly camera (6DOF)
• ImGui debug panel

Cthulhu is being developed as a long-term engine project with a focus on:

• Learning by building
• Visible progress through milestones
• Clean foundations without premature overengineering
• Practical FPS-specific design decisions

• Additional light types (spot lights)
• Omnidirectional shadow mapping (point light shadows)
• Cascaded shadow maps
• Full PBR material system
• Level editor
• Lua scripting
• miniaudio integration (library vendored)
• Asset pipeline improvements
• Expanded ImGui editor interface
• Instanced rendering
• Spatial partitioning (octree / BVH)

Cthulhu/
├─ src/             # Engine source files
├─ include/         # Engine headers
├─ SandboxSample/   # Standalone game sample using the engine library
├─ assets/          # Models, textures, scenes, etc.
├─ shaders/         # GLSL shader files
├─ Libraries/       # Third party dependencies
└─ build/           # Build output

KalaMake — build system used for Cthulhu, developed by Lost Empire Entertainment.
Big thanks for making a clean and capable build system that made this project easier to set up.

Lost Empire Entertainment — if you want to explore their broader ecosystem of tools and engines, check out their GitHub.
Note: their Elypso Engine is currently being reworked.