you can grab Metro 2033 Redux for free on Epic Games Store. You can get this game for free at Epic Games Store until 5 PM CET Tuesday, December 23nd 2020.

Metro 2033 Redux is the definitive version of the cult classic ‘Metro 2033’, rebuilt in the latest and greatest iteration of the 4A Engine for Next Gen. Fans of the original game will find the unique world of Metro transformed with incredible lighting, physics and dynamic weather effects. Newcomers will get the chance to experience one of the finest story-driven shooters of all time; an epic adventure combining gripping survival horror, exploration and tactical combat and stealth.

17-12-2020 Cities: Skylines
18-12-2020 Oddworld: New n Tasty
19-12-2020 The Long Dark
20-12-2020 Defense Grid 1
21-12-2020 Alien: Isolation
22-12-2020 Metro 2033
23-12-2020 Tropico 5
24-12-2020 Inside
25-12-2020 Darkest Dungeon
26-12-2020 My Time in Portia
27-12-2020 Night in the Woods
28-12-2020 Stranded Deep
29-12-2020 Solitairica
30-12-2020 Torchlight II
31-12-2020 Jurassic World Evolution

You can obtain your free copy of Alien Isolation from here.