i wouldn't limit the factor to games, but multimedia entertainment in general pushed the general popularity of PCs and such from the "geeky" world into the mainstream.
Now, games did have a major impact on some of the businesses though: Companies like Alienware built their entire business model based on the simple fact that people want to 1) have the latest gadgetry/hardware, 2) show off, 3) have the most fun out of the games that they play. If it weren't for popularity of computer games in the mainstream public, Alienware wouldn't even be in existence.
For PPC's sake, I wish there is a John Carmack for the PPC market. It would definitely propel the PPC market into new areas and increase its popularity.