"White Day" is a first person survival horror with numerous adventure game elements and a plot background based on the ancient Chinese religious studies of Taosim (mainly Wu Xing, Feng Shui and Qi). The game has multiple difficulty modes that you can choose from, with hard and real difficulties only unlock later.[note 1]
There are no weapons in White Day, you assume the role of Lee Hui-min, a typical high school boy student cooperating with Han So-yeong, Seol Ji-hyeon and Kim Seong-ah; who are also trapped in the school with you, you have to go through the school and ultimately escape unharmed by the numerous threats that want you dead.
The game uses a multiple choice based conversational system, which is rather known as Conversation Tree or Dialog Tree, a common feature in adventure games. The dialog choices you make when interacting with the NPCs affect the story progression and the ending you get. There are 8 different endings you can get, each determining which girl you end up escaping with (or dying with, depending on the girl).
When a Janitor finds you, he will blow his whistle and proceed to chase you wherever you go until you outrun him or lose him by hiding. If he catches up to you, he will repeatedly hit you with his bat until you are dead. The Janitor finds you much easier if you make loud noises (running, opening doors etc..) and whether you are hiding in the dark or light won't affect how easily you can be discovered as he wields a flashlight in his left hand at all times.
Falling from a height, walking into ghosts or taking damage from other hazards will cause the screen to flash red and increase the rate of your heartbeat, which is heard in-game. Running for too long will make you tired and also increase the rate of your heartbeat.
Health items such as Soyabean Milk, Lunch Boxes and Coffee Cans can recover your stamina and health and can be obtained by inserting 500 won Coins in Vending Machines placed in hallways and rooms around the school. The game also has several equipable items that assist you through your journey such as the Matches, the Lighter or the Flashlight.