A timeline of the Half-Life universe can be made by gathering known dates. Several retcons having been made since the release of the first game, because it is still being written as of today (2017), and because technological limitations have changed in the intervening time, a complete official Half-Life series timeline will probably never be made, since it could probably make the writers contradict themselves and limit their creativity for possible subsequent episodes. Despite that, general events can be organized in a chronological order, around known dates.