4. Resident Evil 6’s transforming enemies
Resident Evil 6 is plagued with problems, but--ironically--the infected enemies are one of its best features. Resident Evil has thrown transforming enemies at me before, first with Las Plagas in RE4 and then the Majini in RE5. However, the J’avo and Chrysalids in RE6 morph in completely random ways. Each change is a horrifying surprise.
They start as shambling corpses, and then they turn into the cocoon-like Chrysalids. Here, they morph again into one of many different variants. You may see the quick and agile Strelats, the slow and strong Napads, or the airborne Mesets, but you’ll never know what’s coming until it’s drooling down your neck. It's a really neat idea, and something that more horror games really should emulate. For me unpredictable, erratic enemies are 100% more frightening than any cheap, jump scare.