Most significant among the new stuff here is the inclusion of a virtual reality mode. A new DLC story chapter called "Blood Ties" will work with the PS VR system; it'll also work as a standalone chapter without the VR headset. There's also a second new story mission called "Lara's Nightmare" and a co-op addition to the game's "endurance" mode. That co-op mode lets two players team up and try to survive as long as possible to get onto the game's leaderboards.
Another new addition to the game is an even harder difficulty level for the single-player campaign known as "extreme survivor." All of the game's checkpoints have been removed, so the only way to survive is to find enough resources to light campfires where you can save your game.
There are a few other extras included, mostly just new visual outfits to pay homage to the way Lara Croft has evolved over the years. Somewhat hilariously, you can replay the main story with five different low-fi polygon-based character models, which will surely look goofy as hell next to the more realistic, high-resolution characters and environments.
Naturally, all of the game's previous DLC is included, as well -- that includes another three-hour story mode expansion, and a bunch of custom outfits and weapons. And if you bought the season pass for Rise of the Tomb Raider on the Xbox One or PC, you'll get all of this new content for free, as well.