Actually, yeah. It was seven (or eight? not sure, I think there was one more coming maybe?) side quests directly tied to one additional tomb each. As individual piece of content they could come off underwhelming, but when they are embedded into the main game (or if you play them in one go after the fact like I did) they are actually a lot of fun.
Give the game a chance, guys. If you, like me, always kinda begrudged the way Tomb Raider kinda turned into Uncharted with the Reboot and liked the improvements they made with Rise, then this game could absolutely be for you. There is a way bigger focus on exploration, puzzles and platforming this time around and that is truly what Tomb Raider was always about for me.
Also, consider turning off all the "you can climb this way"-markers in the difficulty options. You know, how Uncharted always turns cliffs you can climb yellow or whatever color? Tomb Raider did the same thing, turning everything you can climb white. Turning that off completely changed the game for me and made it so, so much better.