Alternatives to Raze

2D and 3D game engine

Real-time strategy game engine for Westwood games

C# scripting capable version of Godot game engine

Enhanced source port of Doom, Heretic, and Hexen

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

Open-source engine for Heroes of Might & Magic III

Open-source continuation of Bungie's Marathon 2 game engine

First person shooter engine

Engine for iD software's Quake

Game engine for development of desktop, mobile and web games

Complete development tool for making 2D games

Adds an OpenGL renderer to the ZDoom source port