It seems like a lot of pre-1980 game shows made use of "darkness" as a special effect in their opening sequence. The most common way was to begin with a darkened stage, then quickly bring up the lights as the players and/or host was introduced. The stage wasn't completely dark; you'd often have conspicuous strings of light bulbs, either steady, blinking, chasing, or progressively turning on. There might also be strategic backlighting effects to silhouette the show's sets.
One textbook example of this was Match Game ‘7x. After introducing the celebrities via that “flipper”, we’d see a darkened set. The word “Match” would diffusively turn on, then “Game” all at once, then “‘7x”, after which the stage lights would quickly brighten as the turntable rotated.
Another example, albeit a distant memory, was Password, I think from 1971. In this case, the show began with the camera zoomed in on the chase lights in a dark studio. The camera then zoomed out enough to make out the word, then the shape of the studio, then the lights came on. (Though I’m not sure they always did that that incarnation of Password. I seem to recall that for the first episode or two, they started out with the studio fully lit and the camera zoomed in on the word Password flashing on and off. They then zoomed out as usual.)
One reason that the darkness special effect was so common, IMHO, is that it was easy enough to pull off with the technology of the time. When TV cameras were tube-based, you needed a LOT of light to produce broadcast-quality programs. I seem to recall being advised to not even look directly at the Fresnel studio lights for danger of hurting your eyes. So it was easy to depict a darkened stage by merely dimming the stage lights to less than high-noon brightness. Over time, TV camera tubes became more light-sensitive, and today most studio TV cameras don’t even use tubes, but rather CCDs to capture the image. As such, while studio lighting still needs to be set “just right”, the foot-candle reading in the camera field doesn’t need to be nearly as high.
Some gameshows used darkness for effects other than the show’s opening. One example was on The Dating Game (original), where they kept each of the 3 bachelors silhouetted in darkness until they were introduced, one-by-one. (Same with the less-common 3 bachelorettes, except they superimposed a lacy heart frame). And a rather odd example was found in the mid-’70s show Baffle. When they “turned off sound” in each player’s booth, they also turned off the stage light in there, making it appear that they were sitting in darkness. (I used to ask myself, as a kid, what being in the dark had to do with whether or not you could hear what was going on. But anyway.)
And of course, many gameshows dimmed the main studio lights, perhaps selectively, as a backdrop for the closing credits. This was done on some variety shows as well, and even some local or national news programs.
