Cataclysm: Dark Days Ahead (CDDA) is an open-source survival horror roguelike video game. Cataclysm: Dark Days Ahead is a fork of the original game Cataclysm. The game is freely downloadable on the game's website and the source code is also freely available on the project's GitHub repository under the CC BY-SA Creative Commons license. The game is currently largely developed by its community. Rock, Paper, Shotgun named CDDA one of "The 50 Best Free Games on PC" in 2016.