Open source port of Ultimate Tapan Kaikki

Open source port of Tapan Kaikki 4: Bloodshed

A 3D two-player arena combat game, featuring characters similar to a popular construction toy

An open source re-implementation of Caesar III

An open source re-implementation of Caesar III

Death Rally engine reimplementation

🎮 · Jazz² Resurrection: Open-source reimplementation of Jazz Jackrabbit 2

Open Source real-time strategy game engine for early Westwood games such as Command & Conquer: Red Alert written in C# using SDL and OpenGL. Runs on Windows, Linux, *BSD and Mac OS X.

OpenTTD is an open source simulation game based upon Transport Tycoon Deluxe

Modern "Jedi Engine" replacement supporting Dark Forces, mods, and in the future Outlaws.

GZDoom is a feature centric port for all Doom engine games, based on ZDoom, adding an OpenGL renderer and powerful scripting capabilities

An open-source port of the scrolling shooter Tyrian.

OpenJazz

ScummVM main repository

ResidualVM main repository

An open-source Tomb Raider 1-5 engine remake

Classic Tomb Raider open-source engine

Open-source engine for Heroes of Might and Magic III

An open source re-implementation of RollerCoaster Tycoon 2 🎢

Free (as in freedom) open source clone of the Age of Empires II engine 🚀

Widelands is a free, open source real-time strategy game with singleplayer campaigns and a multiplayer mode. The game was inspired by Settlers II™ (© Bluebyte) but has significantly more variety an…

An open source, turn-based strategy game with a high fantasy theme.

The Dawn of Civilization mod for Civilization IV: Beyond the Sword, based on the popular Rhye's and Fall of Civilization mod.