Little marvel that brightened up many teatime, often thought of as the forerunner of The Crystal Maze.
Three rent-a-celeb types were guided around a series of mental and physical puzzles devised by Patrick Dowling. The puzzles usually involved logical thinking with some lateral twists.
The show had quite a cute backplot. Set on the planet Arg, the inhabitants (sometimes human, sometimes dragon shape-changers called "the Argonds") put the contestants through their paces, including:
Dorgan, the friendly helpful one that got the contestants under way.
Gandor the Butler, who used an ear trumpet to help him see, and wore his glasses to help him hear.
Dagnor, the backwards-talking Australian who would compliment contestants with a "Doogy Rev" if they'd done well.
Rangdo, the shy ruler of the planet that took the physical prescience of an Aspidistra (or, later, a teapot).
Also of note is The Red Salamander, a mute but very tall lizard who often played against the contestants in the Drogna game when competing for prizes such as green cheese rolls (see later).
As you may have noticed by now, nearly everything to do with the game was an anagram of "dragon", including the obligatory salute "Gronda, Gronda". The currency on the planet was the Drogna, which were clear plastic pieces containing a coloured shape in the middle. The value of the drogna was equal to the number of sides on the shape, multiplied by their position in the rainbow (hence a sign saying Richard of York Gained Battle on the wall).
The Drogna Game
One of the initial challenges, the "drogna game", was a floor-tile puzzle that made use of these shapes. A particular logic applied to where you could or couldn't move (e.g. you can only move to a square with the same shape or colour).
One of the sub-games involved the contestants finding Lesley Judd, who would turn out to be The Mole and attempt to sabotage subsequent challenges.
Other games were wide and varied, but included stepping through a series of poles, guiding a mouse around a computer maze, interacting with the Argonds and their strange quirks, defeating the Red Salamander at the Drogna game, guiding a fellow player out of a pitch-black room, gentle physics problems, and solving codes.
Although the challenges in each programme were all variations-on-a-theme throughout the series, the final round in later shows was always the superb Vortex game, where the contestants had to cross a hexagonal lattice.
They had to move without stepping on the same space as the vortex, which would "evaporate" them. The contestant and the vortex (which was invisible to the contestants but visible to the viewers) would take one turn each move.
Only by logic, guesswork, and the occasional use of green cheese rolls (which could be used to identify where the vortex was) could the team get across safely to the waiting shuttle. Otherwise they had to walk home, and it's a long way from Arg to Earth. Nail-biting stuff.
One other feature worth mentioning is the "phone links" in later series where one of the hosts would ask children at home what they should do. Didn't really add much to the game, truth be told.
Much celebration when a contestant managed to get across the Vortex grid, even though it meant Rangdo (the Aspidistra) got very angry indeed.