When you finish the game, it autosaves in the same slot you were using previously. After the end credits, there's a short cutscene with Lara and Ana after the events in the Chamber of Souls. Then you'll have the opportunity to reload your last save. Even if you have 100%, I encourage you to do this in order to see a final cutscene with Lara and Sofia back in the Geothermal Valley near the Valley Farmstead Base Camp. If you missing anything, you can now use the extensive network of camps to fast travel between the areas to take care of unfinished business.
Once you've completed the story, you will be able to return to Syria, which now has 3 fast travel camps, shown at the bottom of the in-game world map.
Unlike the last game, TOMB RAIDER (2013), you do not need to complete all skill and weapon upgrades to get 100%.
For the collectibles requirement, you basically need all of the items listed under the "Region Summary" on each in-game level map. Not all levels include all types of collectibles. Finding all 10 codices requires that you complete all the optional Challenge Tombs and also the story level "The Orrery," which includes a codex.
It is not necessary to find the Explorer Satchels and Archivist Maps, but these can help you locate other collectibles by revealing Documents, Relics, and other points of interest, such as Crypts, on your in-game map. You will need to decipher all of the Monoliths, since it is not possible to find the Coin Caches without doing so.
Challenge items, such as the lanterns in the Prophet's Tomb and the Cosmonaut posters in the Soviet Installation, are not shown on the in-game map but are indicated on my annotated level maps. These are linked from each walkthrough page as well as from the Quick Collectibles Guide.
The documents in the series Sessions, Research Notes, and Crypts of the Founders, and Camp Journals, Codices, and the various mural inscriptions (Byzantine Inscriptions, The Journey, Soviet Crests, and Crypt Murals) do not count toward 100% completion, just the documents you can actually find while exploring the game world.
For help using the in-game map to check your progress, refer to the Map/Objectives/Inventory Screens section of the Controls page.
To see which Challenges have been completed, open the in-game map and click the ---- button (PC), or press Triangle (PS4) or -- (Xbox). For details see Challenges and Missions on the Controls Page.
The collectibles the Baba Yaga: Temple of the Witch DLC do not count toward 100% completion. Note that while you are playing this expansion, you may see an extra active mission in the Region Summary for a different region. This seems to be a minor glitch that fixes itself once you complete the DLC.
When you achieve 100% completion, you'll unlock the No Stone Unturned Achievement and also receive the THUNDERCLAP SHOTGUN. To equip it, go to any base camp, access the Weapons menu, select the Shotgun, and then scroll to the right, past the Tactical Shotgun, to select Thunderclap.
If you're not sure which collectibles, missions, or challenges you're missing, here's how to find out:
Open the in-game map by pressing Tab on the keyboard or View/Back on a controller. Then use the direction keys or left stick to examine the various areas on the world map. As you hover over each area, you'll see the percentage completion and Region Summary on the left side of the screen. (screenshot) When you find a region where you are missing something, zoom in to see more detail. You may be able to see the missing items on your map. (screenshot)
Undiscovered collectibles are bright white on the in-game map, while found items are grayed out. However, some items do not appear on the map at all until Lara approaches them in the game or you find find a clue, such as an Explorer Satchel, Archivist Map, or that marks them on your in-game map.
If necessary refer to the walkthrough and/or Quick Collectibles Guide for that level to help locate the missing item(s). Each one includes an annotated level map with the collectibles numbered to correspond with the written walkthrough. The challenge items are also included on the maps as colored dots, with a different color for each challenge. If you compare my maps with your in-game map, you should be able to find what you're missing. Most levels in the walkthrough also include a section at the end on revisiting the area later in the game. These notes may be helpful, especially for levels where things change after you pass through and items that can only be obtained using special gear.
If you need help finding anything, please feel free to ask.
†UPDATE HISTORY: 3/23/16 - Page first posted online. 12/10/17 - Made a few minor tweaks for clarity.
1/13/18 - Added the printable checklist and a few additional notes about which documents are required.
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