28 Days Later

The sprinting infected is 28 Days Later's invention and Train to Busan runs on it entirely: a crowd that converts in seconds, so distance stops being safety and every carriage door becomes the plot. Yeon Sang-ho's additions are his own, a commuter train as the confined space and a fund manager who has to stop optimising, but the creature and its speed come from Boyle.

Boyle and Garland have both acknowledged Romero, while being careful that these are not zombies but the living infected. What carries over is Romero's whole argument rather than his monster: the dead are the setting, and the film is about the survivors turning on each other indoors. The soldiers at the manor house are 28 Days Later's version of the posse who shoot Ben. Boyle has also named The Day of the Triffids for the empty-city opening, which is why this is MEDIUM rather than HIGH.