Musuu (夢数)

Overview
Musuu (夢数) (Dream Number) is a Japanese Yume Nikki fangame produced by marisyan (まりしゃん), co-creator of dream book and sick mind. It was developed in RPG Maker 2000.

Gameplay
Like most fangames, the player is confined to the protagonist's room, only being able to step out to the balcony. Inside the bedroom the player can either save at the desk, turn a space heater on or off, or sleep in the bed to enter the dream world. Uniquely, effects are referred to as Numbers, and allow the main character to match the appearance of the NPC the effect's collected from.

Controls

 * Move - Arrow Keys
 * Interact/Select - Z/Space
 * Open Menu/Cancel - X/Esc
 * Run - Shift

Plot
It stars Rei (零), a boy refusing to leave his room. Judging by Rei's attire, the meager heating in his room and the weather from his balcony, it can be inferred that he stays in his room due to a snowstorm or similar event.