The Sick Sister and the Unsmiling Me is a text-based simulation game where the player can have a sick sister. The game is very simple, the player only need to click on the screen to have a conversation with the sister, at the same time, the game will have a "sickly value", according to the different relationship between the player and the sister, the sister's sickly value is different.

Players can increase their emotion level by talking to their sister, and the higher the emotion level, the more different the content of the conversation and the tone of the sister's voice will be. The more you talk to your sister, the more your conversation will be different, and the more you talk to your sister.