9. Attack Of The Flood - Halo: Combat Evolved
The first half of the original Halo's campaign is a pretty straight-up sci-fi military shooter, propelled forward on the strength of its breathtaking environments, pitch-perfect combat, and thoroughly entertaining vehicular interludes.
But then Bungie decided to introduce the Flood.
The mid-game chapter "343 Guilty Spark" is a masterful exercise in slow-burn suspense, as players become increasingly aware they're about to encounter something horrific, before they're set upon by a fleet of the parasitic critters.
Like Uncharted, the game switches gears into eerie horror territory at this point, though that feeling of dread persists far longer than it does in Naughty Dog's action-adventure game.
343 Guilty Spark is followed up by perhaps the single most infamous mission in the entire Halo franchise, "The Library," a relentless, exhausting slog of a survival mission in which players must fend off wave after wave of the Flood while navigating the confusingly repetitive environment.
As much as fans may complain about it, though, it certainly puts them in the headspace of a soldier facing insurmountable odds against a seemingly never-ending enemy.
For a game that was largely marketed as an action-centric space shooter, that's quite the surprising turn.