PK XD is a child-friendly, social sandbox game released in 2019, available on multiple mobile and desktop platforms. It targets younger audiences and focuses on open-world, persistent social interaction. Based on mobile store rankings, global reach, and ongoing social media activity, it continues to attract a substantial user base, with daily active players likely in the low-to-mid six figures. While not as massive as major legacy MMOs, its persistent social world and open environment qualify it as an MMO by standard definitions.