Throughout the campaign and side missions, you can find hidden SDF Intel data pads. Collecting these provides additional lore about the Settlement Defense Front, their motivations, and their technology. There are a total of 30 pieces of SDF Intel scattered across various missions. Each piece is typically a small, glowing data pad that emits a subtle hum, making it easier to locate when you are nearby. They are often tucked away in corners, behind cover, or in less-traveled areas.
While not essential for completing the game, collecting all SDF Intel contributes to the 'The Longest Day' achievement/trophy and offers a deeper understanding of the game's universe. We recommend keeping an eye out for them during your first playthrough, but if you miss any, you can always replay missions via the 'Mission Select' terminal on the Retribution's bridge. Consult a dedicated collectible guide if you're struggling to find specific pieces, as some are very well hidden.