ORTHOISO is a platformer puzzle game about optical illusion. Our game uses orthoganol projection that makes distant objects in 3D look close on 2D screen. This allows the player to achieve impossible things in real world. There are 3 different views in the game. Player needs to switch between these views to solve the puzzle. There are many different mechanics based on optical illusions. The story is a about a little frog named Iso, whose father is a famous adventurer. In one recent adventure, Iso's dad went missing. Iso decided to start his own adventure to find his dad.