"You are your planet's last hope. Your corrupted planet explodes. You have to time travel through white holes with primordial essences to prevent the inevitable collapse of your home."

577 Rhea is a planetoid in our solar system, belonging to the asteroid belt. Sier takes its name and develops a stochastic space exploration game, with soft gravity physics.  With a high degree of abstraction and a visual minimalism in which the binary and the algorithmic are exposed without "skins" or disguises, the game confronts us to handle concepts that mean nothing in the digital domain, such as time travel or space displacements.  Playing with the pure code, with its rules, getting into its coordinates, its "physics", its own logic, will you manage to guide 577 Rhea to her home?