It's showing up for me in the App Store but nothing happens when I click "Try It Free" so I'm guessing my iCloud profile hasn't been added to the rollout just yet.

I don't have high hopes for it TBH, but then again I don't currently play any games on iOS.

Incoming bold claim: It will be bigger than Steam in 5 years.

In five years if they're running ARM processors on desktop/laptop/mobile/tv devices there is no stopping them from completely taking over. The best part about the platform is they support family plan out of the box and the apps are discouraged from using any type of 'in-app' purchases/upgrades. Not sure how long that will last.. but Apple are definitely paving the way for perpetual incomes for those game developers who remain relevant by constantly updating/improving/enhancing their games.