Release Usernames from unused accounts

Accounts that are created and have not logged playtime for six months after its creation should have their usernames released. This would prevent the ability to squat accounts on names that never get used and allow people to change usernames without fearing a squatter taking their old names.

To prevent abuse of the system, it can require minimal genuine activity (eg. opening a world, changing settings, or slightly longer playtime) to avoid bots automating the opening of the game once to bypass the criteria.