While I’m a fan of the Stalker games, there’s something about the more linear nature and, ironically, on-rails experience that the Metro games deliver. With a tense atmosphere, mutated creatures, and factions split within the underground of a demolished Russia, the Metro series might be some of my favorite FPS games of all time—and with Metro 2039 almost here, now’s the chance to catch up on the series for less than $9. That’s all three of the games released so…