The Italian Competition Authority (AGCM) has into Microsoft-owned game studio Activision Blizzard, centered around the mobile games Diablo Immortal and Call of Duty: Mobile. The AGCM alleges the free-to-play games use “misleading and aggressive practices” to encourage in-game purchases.

Regulators say the games rely on a “deceptive user interface design” meant to encourage longer and more frequent play sessions while bombarding players with reminders and opportunities to spend real money in-game. Players might be reminded to buy a limited-time item before it’s gone or urged not to miss out on rewards, with in-app messages and push notifications that reach players during and outside gameplay. The authority also raised concerns about virtual currency and in-game currency bundles that can make it harder to understand real-world costs.

Parental control settings are also being scrutinized as the AGCM says the default settings are too permissive, such as allowing in-game purchases and unlimited play time. The watchdog will also investigate potential violations of consumer contractual rights and practices that may encourage players to unknowingly give up those rights, such as the EU’s .

Free-to-play games have long leaned on loot boxes and other in-game purchases to drive monetization. Unlike full-priced games like , these systems can blur the line between natural progression and pay-to-win. For an idea of how quickly costs can add up, consider one player who reportedly on Diablo Immortal.