Mutants in Orbit is a role-playing game authored by which British designer/publisher? 
Mutants in Orbit: Mutants in Orbit is an adventure and sourcebook for the "After the Bomb" and "Rifts" role-playing games, authored by James Wallis and Kevin Siembieda. James Wallis (games designer): James Wallis is a British designer and publisher of tabletop and role-playing games.
James Wallis