Today, 343 Industries announced that it will be offering a 4K upgrade for Halo 5: Guardians to coincide with the release of the Xbox One X. But that's not all, as the firm is also adding four more Halo games to the Xbox One Backward Compatibility list, on top of the existing Halo Wars, Halo: Reach, and Halo: Spartan Assault.

Coming to the list later on this year, they'll include Halo: CE Anniversary, Halo 3, Halo 3: ODST, and Halo 4.

Halo: Combat Evolved Anniversary

Created in celebration of the 10th anniversary of one of the most beloved franchises in gaming history, Halo: Combat Evolved Anniversary is a spectacularly remastered version of the original Halo campaign. Bundled with seven of the most popular multiplayer maps in Halo history ready for Xbox LIVE, Halo: Anniversary will include a bounty of new features including cooperative play over Xbox LIVE, Achievements, new challenges, and new fiction to uncover.

Halo: CE Anniversary isn't currently available to purchase from the Xbox Store, so there is no price yet; however, the original Xbox version of the game is listed for $9.99.

Halo 3 ($19.99)

The epic saga continues with Halo 3, the hugely anticipated third chapter in the highly successful and critically acclaimed Halo franchise created by Bungie. Master Chief returns to finish the fight, bringing the epic conflict between the Covenant, the Flood, and the entire human race to a dramatic, pulse-pounding climax.

Halo 3: ODST ($14.99)

Halo 3: ODST drops you into the world of the legendary Orbital Drop Shock Troopers as you embark on a dangerous mission to discover what was behind the Covenant’s attack on the city of New Mombasa. Halo 3: ODST’s gripping story and co-operative campaign will give all fans an exciting new perspective on the Halo universe.

Halo 4 ($19.99)

The Master Chief returns to battle an ancient evil bent on vengeance and annihilation. Shipwrecked on a mysterious world, faced with new enemies and deadly technology, the universe will never be the same. Enlist aboard the Infinity to experience Halo’s original multiplayer and Spartan Ops - innovative episodic fiction-based co-op missions.

It's worth noting that these games don't exactly expand the library of games for the Xbox One; instead, they eliminate a barrier to entry by allowing you to play your old games. Halo: CE Anniversary, Halo 3, and Halo 4 are all available as parts of Halo: The Master Chief Collection, which also includes Halo 2: Anniversary in one package for $29.99. Halo 3: ODST can be added on for $5.

But one benefit that you will get from playing the backward compatible games is that every Xbox 360 add-on map will be available for free, once the games are added to the Backward Compatibility program, which is to say, later this year.