Open-source alternatives to Unreal Engine

2D and 3D game engine with a full editor — Godot Engine – Multi-platform 2D and 3D game engine

↔ alternative to Unity、Unreal Engine

Cross-platform game engine with editor — A complete and cross-platform game engine designed for flexibility, performance and fast iteration.

↔ alternative to Unreal Engine

Blender-integrated game engine and editor — UPBGE, the best integrated game engine in Blender

↔ alternative to Unity、Unreal Engine

Open-source 3D game engine with Vulkan and D3D12 — AnKi 3D Engine - Vulkan and D3D12, modern renderer, scripting, physics and more

↔ alternative to Unity、Unreal Engine