I believe he’s referring to “near misses” being illegal in some jurisdictions (Nevada being one). Slot machines are not supposed to be engineered to make it look like you almost won a large jackpot, but didn’t.

Candy Crush seems to specialize in near misses, for example by creating levels where almost all of the achievements required to pass a given level are easy, and then one is next to impossible. You don’t keep $1 billion+ per year coming in on a years-old game without some serious psychological tricks.