Are there any favorite resources online that you guys know of, or any good books in addition to the games that cover the halo universe/lore in chronological order?
I’d check out this thread. But for a short answer, get Halo Mythos. It’s a chronological summary of all the major points in the Halo Universe from Forerunners to the beginning of Halo Wars 2.
Have a check over this thread from cia391
https://www.halowaypoint.com/en-us/forums/db05ce78845f4120b062c50816008e5d/topics/halo-story-and-where-to-find-it-v3/c0051ce8-49a3-4ab9-bd73-b77d9e73174a/posts?page=1