The opening chapters of the Metro 2033 Redux and Metro: Last Light Redux are available for free on Xbox One and PlayStation 4!
You can play the first eight Chapters up to Dead City in The Metro 2033 Redux Trial and the first nine Chapters up to Theatre in The Metro Last Light Redux. After that, if you decide to upgrade to the full-game versions, all of your saved games and progress will be transfered as well.
What are you waiting for? Go and play the first eight chapters of Metro 2033 Redux and the first nine chapters of Metro: Last Light Redux right now, because they are free!