Research Books are items that may be used as fuel for Fire Starting and have the same weight (0.5kg) as normal books. However, they may also be read, which grants skill points to their respective Survival Skills when completed. Because of this, Research Books can be found in both the Fuel and Tools categories. Attempting to burn a Research Book that has not been fully read will give a confirmation warning before it can be burned. Once a Research Book is fully researched, it will no longer appear in the Tools section of the Backpack.
Multiple copies of the same book may be researched for additional benefit.
Research Books are scattered throughout all regions similar to normal Books, but are much rarer and have unique detailed covers.
Books cannot be read in the dark or if the player has 0% Warmth, Fatigue, Thirst, Calories or any negative Affliction. Reaching 0% in any Needs while researching will immediately end the research session and negate any progress for that research attempt. (i.e., if you complete 59 out of 60 in-game minutes of a 1-hour research session, and your character begins starving before completing the last minute of research, the character immediately forgets everything they researched in the last 59 minutes).
Frontier Shooting Guide cannot be read once Rifle Firearm reaches Level 4, displaying the message "Your Skills are too advanced to research this." This is the only Research Book that has a Skill Level restriction.
On Interloper, researching Skill Books burns calories at the rate of "Standing" (125 cal/h).
Since Skills cap at Level 5, any category of Research Books related to that Skill cannot be read, and can only be used as fuel at that point.
Spoiler Warning: This page may contain spoilers from the story of The Long Dark.
In Wintermute, items that resemble Research Books may be found, but these items are instantly turned into Collectibles when picked up and instead unlock side missions.
Survival Skills levels are dependent to each save file.
All varieties of books and research books may spawn regardless of Survival Mode (or loot settings, in Custom); this includes firearm-related books on Interloper difficulty.
The Achievement "Penitent Scholar" requires reading all varieties of Research Books in a single save file.
The Feat "Book Smarts" increases the skill points gained from completing a research book by 10% (e.g. with the feat active, reading a "Small Arms Handbook" yields 11 revolver skill points instead of 10). Like all feats, "Book Smarts" tracks its progress across all save files (except Custom Sandbox).
Research Books originally featured more varied sizes and cover art; however, currently their art and size are more uniform.
