Metro Franchise Sales are now underway on GOG.com* and Steam. These celebrate the 15th anniversary of 4A Games' FPS series based on Dmitry Glukhovsky's novels set in the Moscow Metro system following an apocalypse. This includes a 100% discount as part of the promotion, and you can pick up Metro 2033 Redux for free on GOG.com and Steam. You have a couple of days to collect and the game will added to your library (protip: the GOG.com version is DRM-free, so it's more "for keeps" than the Steam edition). This remaster of the first installment in the series illustrates how time flies, as it is now over a decade old, after being released only four years after the original. Here's the description:

The year is 2033. An entire generation has been born and raised underground, and their besieged Metro Station-Cities struggle for survival, with each other, and the mutant horrors that await outside. You are Artyom, born in the last days before the fire, but raised underground. Having never ventured beyond the city limits, one fateful event sparks a desperate mission to the heart of the Metro system, to warn the remnants of mankind of a terrible impending threat.

Your journey takes you from the forgotten catacombs beneath the subway to the desolate wastelands above, where your actions will determine the fate of mankind. But what if the real threat comes from within?

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.