Restrictor was being developed by Arc Developments during the early 1990s for the Commodore Amiga (and also reportedly the C64). It was to be an original title from Arc, developed for Thalamus where you could drive and also fly, with around 4 planets to explore and various alien waves to fight.
For years there has been a screenshot showing the driving section from the game, but contributor Ross Sillifant located some more scans from French magazine Joystick, issue 19 (September 1991), which shows one of the flying vehicle levels, but what also seems to be a sort of platformer section where you control a person.
Development seemed to drag on for a while, when Thalamus eventually went under around 1993 time. Taking a number of titles with it in the end.
At this stage we know little more about the title, but hope to hear from Richard Underhill in the future to find out what happened and just how far this game got.