28 Years Later arrives in a vastly different cinematic landscape than its predecessors. The "fast zombie" it popularized is now a trope. The film’s challenge was to innovate. The premise of a mutated virus and a deep dive into human depravity suggests Boyle aimed for a more existential, almost Heart of Darkness -style horror rather than a simple survival thriller.
For a better viewing experience, it's highly recommended to watch "28 Days Later" (2002) before diving into "28 Years Later." https://www.hdfilmcehennemi.ltd/film/28-yil-sonra-izle/