They describe a leaderboard built from server members' shared gaming activity, while actual rollout remains unconfirmed.
When It Appears
“Who has played the most unique games?” can appear on a server view that ranks shared gaming activity and shows a timed competition when Discord displays the competition question ranking who played the most unique games.
When “Who has played the most unique games?” is shown, the current step is presenting the competition question ranking who played the most unique games.
Search Intent
A user who saw “Who has played the most unique games?” in Discord is likely searching to confirm that it means the competition question ranking who played the most unique games, where it appears, and which state it describes.