Throughout the campaign, there are 45 pieces of collectible Intel hidden across all missions. Finding these pieces of Intel provides additional backstory and lore about the KVA, Atlas Corporation, and the global conflict. Each mission typically contains 3 pieces of Intel. They are often tucked away in less obvious corners, behind cover, or on desks in enemy strongholds. Collecting all Intel unlocks the 'Ferrum Absconsum' achievement/trophy. We recommend replaying missions on Recruit difficulty after your initial playthrough to focus solely on finding these without the pressure of intense combat. Listen for a distinct electronic chime when you are near a piece of Intel, indicating its proximity.
