Free game promos are easy to find, but Epic is going one step further by offering an entire game trilogy for no charge. The Epic Games Store is offering all three Tomb Raider reboot titles (Tomb Raider, Rise of the Tomb Raider and Shadow of the Tomb Raider) for free between now and January 6th at 11AM. They're Windows-only if you grab them from the EGS, but they're also complete versions that include post-launch DLC.
Your experience with the games may vary. Some will highlight Rise of the Tomb Raider as the star of the series, and aren't always enthusiastic about Shadow. And expect to do a lot of crafting in between adventures. They're solid releases as a whole, though, and represented a return to form for a franchise that many felt had lost its way. At the least, they'll serve as good training tools for Uncharted's eventual PC launch.