Leaving aside the fact that an IQ score in the 190s is absurd (no one has curved a test over a large enough population for such an answer to reflect actual score distributions), as far as actual, normed IQ tests conducted by actual psychologists go, it's hard to find a test with a ceiling higher than 160 these days. The Weschler, easily the most popular among these, has a ceiling of 160, and getting a score above the low 140s requires doing very well across most of the individual batteries, some of which aren't especially g-weighted. No, the quiz in Omni is not, as far as most psychometricians are remotely concerned, an IQ test. To define it as such is to destroy most of the meaning of the term.
Occasionally, you see high scores due either to very old versions of the Stanford-Binet that did reach above 160 (it's likely that Ted Kaczynski got such a score) or the use of extensions of the old Stanford-Binet to investigate young people who hit or near ceilings, typically on verbal parts of these tests where raw scores tend to have a little more variance, but extrapolations to actual IQ scores aren't valid today due to the Flynn effect (ie: more young people are properly nourished and in intellectually stimulating environments than were in the early 20th century) and the fact that old versions of the Stanford-Binet weren't necessarily normally distributed along the 15-point sigma most tests are today. Though people have attempted to write on the upper echelons of performance on tests of cognitive ability, there's remarkably little that is peer-reviewed.
The tl;dr of all this is that whenever you hear reports of IQ scores above 160, you can more or less assume someone is talking out of their ass.