This project investigates how to design an architecture in a context of virtual space, and how to utilise the exclusive possibilities of the virtual context.  The main case study about the virtual space and impossible space is based on video games. After analysing the mechanism of building such 'impossible spaces' in various video games, this project conducted an experiment on designing several virtual spaces in the game engine, Unreal Engine 4, to investigate the differences between architecture in the real space and in the virtual space. In addition, another architecture experiment was conducted in an impossible space: a space where gravity is modified to be vertical to the surface of a triangle swept Mobius Strip. Walking in such a space offers an exclusive 'impossible' experience. Such an experience is possible to be presented by the manifestation of Unreal Engine 4.