For me, this helped defined not just how vital a unique atmosphere is to a story but the unique possibilities of telling stories within games. Sure, it's very much a child of Half-Life, but the human and spiritual implications of Metro run far deeper than Freeman's journey. There's a tale in each station, the way the social order is set up — the markets, the beggars, the families and the different facilities for housing, relaxing and even waste disposal. The character of Khan helps protagonist Artyom and the player to understand why different entities and people behave the way they do.
Even the moralistic arc of the karma system encourages the player to try to engage with the world on a deeper level, asking them to consider the stakes and cost of life as they sneak or cut their way through bandits, ideologues and the mutants. Perhaps its implementation is flawed, but it is a system rewarding engagement with the world on a more considered, tactile basis. It helps flesh out 2033's setting not just as a shooting gallery and dungeon crawler but as world separate from ours that we've had the privilege of being granted temporary access to.
With the original Metro 2033 currently unlisted, a pretty important cult hit is now largely unavailable in its original form. Making this available would also help contrast against 2033 Redux and Last Light, enlightening players as to what was arguably improved and what was left behind as the series surged forward. The original 2033 is a rough gem and, despite carrying some of the developer's S.T.A.L.K.E.R. DNA, still stands tall and stalwart amongst its peers.