The world

A walkable room rendered in 3D, with five coloured cubes on a floor. Move with W, A, S and D or the arrow keys, and jump with Space. Turn left with Q and right with C, and look up and down with R and F. Change a cube’s colour with E or Enter while you are facing it, or click it with the mouse. Press Escape to release the pointer. Nothing here is needed to book anything.