They take a popular PC or console game - BioShock Infinite is the latest one - and develop and publish a Mac version, historically released months or years later (though that’s not often the case now), earning ridicule and celebration from a frustrated audience long condemned to second-class treatment.
Except these days they’re actually doing a pretty good job.
Eurogamer has a profile on Aspyr Media, the software house that’s well known for porting Windows games to the Mac (and recently iOS). I had no idea they’ve been around for more than 17 years. It would have been interesting to know more about Feral, too.