Add 0 A.D. to Games (#3493)

README.md

@@ -998,6 +998,7 @@ _Related: [Groupware](#groupware)_
 Multiplayer game servers and [browser games](https://en.wikipedia.org/wiki/Browser_game).
 
 - [A Dark Room](https://github.com/doublespeakgames/adarkroom) - Minimalist text adventure game for your browser. ([Demo](https://adarkroom.doublespeakgames.com/)) `MPL-2.0` `HTML5`
+- [0 A.D.](https://play0ad.com/) - A free, open-source game of ancient warfare. ([Source Code](https://github.com/0ad/0ad)) `MIT/GPL-2.0/Zlib` `C++/C`
 - [EmuLinkerSF](https://emulinker.org) - EmuLinkerSF is an open source Kaillera server. Kaillera is a client/server system that any emulator can implement to enable netplay over the Internet. ([Source Code](https://github.com/God-Weapon/EmuLinkerSF)) `GPL-2.0` `Java`
 - [Hextris](https://github.com/Hextris/hextris) - Fast paced HTML5 puzzle game inspired by Tetris. `GPL-3.0` `HTML5`
 - [Lila](https://lichess.org/) - The forever free, adless and open source chess server powering lichess.org, with official iOS and Android client apps. ([Source Code](https://github.com/ornicar/lila)) `AGPL-3.0` `Scala`