Trivial Pursuit.  (Domark / Oxford Digital Enterprises).

It was was one of the best-selling games ever (measured by market-share) and continued to sell well many years.

Probably unheard of now -- but it represented ground-breaking use of the hardware to get all of the questions and game onto a single disk.  Even the machine code was compressed and decompressed at run time to get it all packed in.

The result was magical.