Telegram CEO Pavel Durov said Catizen, a "tap-to-earn" game built on the TON blockchain, has "earned" $16 million through in-app purchases. "Catizen is a mini-game on Telegram with more than 26 million players. The game has earned $16 million through in-app purchases and donated 1% of that to stray cat rescue," Durov tweeted on Tuesday. Click-to-earn games such as Notcoin, Yescoin, Hamster Kombat and Catizen have attracted tens of millions of users in recent months. Catizen and Hamster Kombat are expected to launch tokens soon.