If you don't snag Forsaken, you'll have an opportunity to play the extended game's PvP/PvE hybrid game mode, Gambit, between November 9th and November 11th.

The giveaway is meant to mark the first anniversary of Destiny 2's PC release, but it's also a strategic move: this puts the game in the hands of legions of people who otherwise wouldn't give it a try. Even if they don't translate to paying customers, they'll expand the size of the community and give veterans a reason to keep coming back.