Revenue is a rough estimate from public install counts × genre ARPD — order of magnitude only.

Knock Knock: Room Defense

<b><font color="red">[Special Rewards] 404 Draws, Character Skin, Random Orange Hero, and Limited Decor!</font></b> When your city becomes the hunting ground for ghosts and monsters... "Knock, knock." Someone's knocking on your door... "Shh, don't make a sound, and don't open the door." Creatures from age-old tales and urban legends are trying to break into your house. Your job? Close the door and defend it with your heroes as your heart pounds with excitement and no fear. Schools, hospitals, hotels, streets, and office buildings—the most mundane locations become thrill-filled tower defense challenges. Get ready for stunning visuals and smooth controls in 5-minute matches! [Five Main Features to Define New Horror Tower Defense]​ ※ Choose your room, close the door, relax, and level up! Ghosts are here and there's no escape? Well—kick back and relax! Choose your room, close the door, and kick back to level up in dreams and summon heroes to build your defense line! It's up to you to defend the ghosts and monsters at night! ※ Strategize to turn the table in the mind game​​ No risking your life, but more than hide-and-seek! Everything from the beds, doors, to your heroes can be leveled up, because the whole room is your defense line. Build the right lineup and plan wisely for every challenge and event. Every win is guaranteed to be rewarding. ※ Immersive visual experience Dive into the immersive eerie world with a distinct gothic chibi-style aesthetic. Is it blood or wine in the cup held by the vampire? Why is the killer with a chainsaw wearing a cute bunny mask? A hundred unique and stylized heroes and ghosts with cute horror elements. ※ Wide selections of avatars and instances Turn into a ghost hunter and explore all kinds of haunted locations—from a train with lingering phantoms, a dormitory echoing with singing at midnight, to a mysterious underground cave. Now, pick your avatar from a wide collection and brace yourself for the ghost chase. ※ Fast and exciting tower defense battle Grab your phone and start a 5-minute no-stress match anytime, anywhere! Quality tower defense fun made simple and fast.