Download & installDownload and install locally. No server needed.
Open-source clone of the original X-Com 👽
GamesOpen-source remakeStrategy
From the README
OpenXcom is an open-source clone of the popular "UFO: Enemy Unknown" ("X-COM: UFO Defense" in the USA release) and "X-COM: Terror From the Deep" videogames by Microprose, licensed under the GPL and written in C++ / SDL.
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.