Alternatives to Unity Editor

2D and 3D game engine

C# scripting capable version of Godot game engine

Open-source, cross-platform game engine designed to be used by everyone

Multi-platform 2D and 3D game engine

Complete development tool for making 2D games

Game engine for development of desktop, mobile and web games

Lua-based game engine

First person shooter engine

Open-source code editor

Multiplayer code editor

Management tool for Unity

3D creation suite