Halo Infinite's multiplayer mode has some hidden modes on PC, which seem only to be accessible if you boot up the game in offline mode.

As spotted by Reddit user u/WickedSoldier991, Halo Infinite appears to include 14 additional multiplayer game modes as yet unavailable in the main online game, including unreleased Arena, Fiesta, Ranked and Tactical mode.

Players aren't typically able to access the hidden modes unless they launch the game in offline mode.