Microsoft's very own Larry "Major Nelson" Hryb has announced, that Halo 5: Guardians will be available for free during this weekend for all Xbox Live Gold members. The offer period has already started, and will continue to Monday morning, January 15.
During the weekend all Xbox Live Gold members can download the game for free, and play campaign, co-op with up to 3 friends and of course test their skills in competitive multiplayer. If you decide to buy the game during this trial period, all your saved progress and achievements will carry over.
At same time Halo 5: Guardians standard and deluxe editions are on sale as you'd expect. Additional info can be found here.
If you want to know what we thought of Halo 5 back at release, head to our review.