How Block Blast Uses Ad Prices to Decide When Players Lose

The author conducted a reverse analysis of Block Blast Android 10.8.2 and iOS 7.4.9, finding that after installation the game downloads encrypted JavaScript rules from a server, among which RewardHighValueAdHarvestTrait requests an unsolvable lethal puzzle when the player has watched three rewarded ads in a row, the current ad price reaches 3.5 times the previous one, and the score exceeds the historical high score by 1000 points. The game also runs an XGBoost regression model on the phone to estimate the player's advertising value eCPM, and uses it to decide revival opportunities and ad types. The author released three evidence packages and reproduction scripts, claiming that the decoded results are byte-for-byte identical to the memory dump of the running app.