The second, in fact, had already been made available last April. On the other hand, Metro Last Light Redux is made available now, after its prequel, Metro 2033: Redux was touched on December 22. The two games are redeemable for free by anyone with a profile on the Epic Games Store, and you can add them to your library either through the PC launcher or through a browser.
The two titles will be available for free until 4:59 pm on February 11, after which time they will return to their normal price. Starting at 5:00 pm on February 11th, it will be Halcyon 6, defined as “a retro strategic RPG set in space that allows you to build your base and that offers capillary tactical combat, crew management, and a promising narrative,” which will be available until the 18th of the same month.