You have to hand it to the kids. They are much more technologically advanced at their age than ever before. So advanced in fact, that there are already two workarounds for the time limits that their parents can place on app usage using iOS 12's Screen Time feature. Screen Time is designed to give parents control over their children's iPhone usage, allowing them to set a cap on how long Junior can use certain apps.
One way to break the cap is to turn the time and date back on an iPhone, giving the user extra time on an app. This can be done even if the phone is already in "down time." The other way is a bit more complex, but a 7 year old happened to figure it out. When this kid runs out of screen time and his apps are locked, he goes to the App Store and downloads a previously installed (but later removed) game using the cloud icon. And the game works without any issues!
Parents can put the kibosh on the latter "hack" by going into restrictions on Screen Time and turn off Install Apps. This will remove the App Store icon from the device. It also will prevent any updates from coming through since that does count as an installation, so keep that in mind.
"When iOS 12 came out I limited my 7-year old son’s screen time through the family share. For a few days I felt like he was playing a bit more than he should, but I couldn’t figure out why. Finally today, my son revealed his hack: When he runs out of screen time and his games get locked, he heads to App Store, downloads a previously installed (but later removed) game through the cloud icon, and it works without limitations! What can I say.. I’m not even mad. That’s impressive."-u/PropellerGuy, Reddit
"I was so excited to turn on the screen time restrictions in the new iOS. Until my 13 year old found a work around within 2 minutes of handing his phone back to him during 'down time' — he went to settings and changed the date/time of his phone to an unrestricted time and voila! Free screentime again."-Anonymous parent
Now that these workarounds have been made public, we could see Apple come up with a fix for both Screen Time cheats.