Polygon has released a series of guides covering hidden skull and terminal locations across three back-to-back missions in Halo: Campaign Evolved: The Library, Two Betrayals, and Keyes. Each mission reportedly contains three skulls and one terminal for players to find while completing the main story objectives.
In The Library, which follows the discovery of the Flood in the 343 Guilty Spark mission, the guide details the Tilt skull (found by climbing a slope after exiting a Flood-infested tunnel), the Pop skull (reached via ramps and jumps opposite a locked door), the Tangent III terminal (located near a fallen marine behind a door opened by choosing the left console), and the Famine skull (found at the bottom of a slope after taking a third elevator down).
Two Betrayals follows immediately after The Library and begins with defeating four sentinels before finding the Alone terminal across a holographic planet walkway. The mission's skulls include Tough Luck, found by flying a banshee to a Forerunner structure emitting a blue beam of light instead of following the marked path; Black Eye, hidden among Flood growths on the opposite side of a set of ramps; and Mythic, which spawns on a pedestal after clearing multiple rooms and a tunnel filled with enemies, including stealth elites and Flood, reached by using consoles and banshees to access separate platforms.
The Keyes mission has players searching a Covenant ship for Captain Keyes while collecting three skulls and one terminal. The Catch skull, available only on heroic or legendary difficulty, appears at the top of a gravity lift after clearing marked enemies. The Blind skull is found by crouch-squeezing past two wraiths to reach a slope. The Consumed terminal is located past a shuttle bay through a series of turns and a fight involving two hunters. The Pinata skull requires meleeing the Flood growth where Captain Keyes was found four times after a cutscene, causing the skull to drop.
Across all three guides, Polygon notes that some skulls require specific conditions to spawn — such as reaching a location within a time limit or disabling gameplay modifiers — and that players have reported certain skulls failing to appear when skulls are enabled beforehand. The guides collectively track players' progression through the Flood-focused sections of the campcampaign, from the library's underground chambers to the aftermath aboard a Covenant vessel.