Microsoft has just unveiled the official lineup of free games that will be featured in its Xbox Live Games with Gold program for December 2015.

And, since the free games for the Xbox 360 are also covered by the Backwards Compatibility service, this means Xbox One owners can access a total of five titles next month, Major Nelson reported.

For Xbox 360 gamers, they'll be able to download "CastleStorm," "Sacred 3" and "Operation Flashpoint: Dragon Rising."

The first game, "CastleStorm," first came out in May of 2013 for the Xbox 360 console before coming out for the Microsoft Windows, PlayStation 3 and PlayStation Vita platforms. The game pits medieval knights against Vikings and features a tower defense type of gameplay. Its 2D-based physics concept allows players to utilize ancient weaponry, spells and ground attacks to take out enemy forces.

"Sacred 3," on the other hand, is a hack-and-slash brawler. As the third major installment of the "Sacred" series, the game was officially released by development studio Keen Games in August of last year. Like other hack-and-slash titles, "Sacred 3" allows gamers to choose characters from different classes. Each class comes with its own unique set of skills which players can utilize to take advantage to complete their goals.

The third game for the Xbox 360 console is "Operation Flashpoint: Dragon Rising." First released in 2009, the game is a military simulation tactical shooter and takes place in a modern setting. The plot of the game follows the brewing conflict between Russia and China that worsened due to a global economic crisis. As the two countries prepare their respective armies, Russia calls on its ally, the U.S., to help reclaim a region.

One the side of the Xbox One, gamers will get two free games starting next month. The first title is "Thief," which came out in February 25, 2014. It serves as a reboot of the entire "Thief" series and centers on the character Garrett. Playing as this master thief, gamers must complete a series of objectives which mainly involve stealing an item from the other characters in the game.

Lastly, Xbox One owners will also get "The Incredible Adventures of Van Helsing" starting next month. Inspired by the novel "Dracula" by Bram Stoker, the game, which came out in 2013, follows the story of a young Abraham Van Helsing as he travels across gothic Europe to hunt down vampires and other monsters.

These five free titles are only available for Xbox Live Gold members. "CastleStorm" will be available from December 1 to 15 while "Sacred 3" and "Operation Flashpoint: Dragon Rising" can be downloaded during the second half of next month.

"The Incredible Adventures of Van Helsing," on the other hand," can be accessed for the entire month of December while "Theif" will be available between December 16 and January 15.