Based on the review, Grand Cash Slots appears to be another fake money-making slot machine game. The app requires you to watch ads to double rewards, and it sets up an ad wall that you must get past by playing more and watching more advertisements to supposedly cash out your earnings. This is a common scam tactic seen in many online casino platforms on the Google Play Store. It's advisable to be cautious and skeptical about such apps, as they often do not pay out as promised.