Halo: MCC Brings the main series of halo finally to PC.

Halo MCC is a new experience on PC, not only do you get to play Halo in stunning 4K graphics, but also using full keyboard and mouse support, Its a first for the series to be ported to PC, last halo to put on PC was Halo 2 Vista back in 2004

MCC is not without bugs, Audio issues, clipping, Multiplayer issues such as delayed/desynced and disconnecting CO-OP, Some weapons not hitting their initial shots, sometimes the game will run poorly on some systems, MCC has a linear progression system, similar to a season pass, so it will take you sometime reach the max level, unlike in Halo Reach: 360, you would earn credits to unlock an armor of your choice.

As of Halo 3:ODST releasing, Halo 3 Multiplayer hit registration was fixed, ODST firefight was added, tons of bug fixes and changes were added, such as challenges being able to be viewed while in game. Further more, a new season pass was brought and celebration challenges.

You get to play as Spartan John-117, an augmented soldier due to experimentation in the Spartan II program.
Made to fight Alien religion known as Covenant, where they worship ancient relics/technology.

In Halo: Reach, the prequel to Combat Evolved. you play as Noble 6, a spartan III tasked with protecting Reach from civil unrest, until the Covenant invaded the planet, you're tasked to fight along side your team to help evacuated the human population before the Aliens wipe out human civilization on Reach.

Halo: Combat Evolved: The namesake of Halo, the start of the main series, you first wake up in a cryotube in the flagship of the UNSC "The Pillar of Autumn" you are tasked with protecting the UNSC Smart AI Cortana, not letting her fall into Covenant hands, mission two, you land on "Halo" an ancient forerunner relic, you are tasked to unlocking its secrets, stopping the aliens from using it as a weapon, and finally, combating the only enemy the Covenant fear; "The Flood"

In Halo 2: You are once again in the boots of John-117, this time on the Orbital Defense Platform known as the Cairo station, You are tasked in defending the homeworld of the Humans. Earth, you battle through the streets of the African City, New Mombasa, using tanks, heavy weapons and support vehicles to fend off the invading Covenant forces, that is until the a Covenant Carrier jumps through slipspace inside the city, causing your commanding officer to chase after, finding another Halo ring.
Part 2 of Halo 2 is where in the first time of the series, you find yourself playing as an Covenant Elite soldier, known as Thel Vadam, AKA The Arbiter, after the Battle of Installation 04 in Combat Evolved, the destruction of the halo ring was your error, your mistake, and the hierarchs of the Covenant punishes you, once you don the Arbiters Armor, you are tasked with assassinating a heretic who is preaching against the covenant's holy religion, finding an old friend along the way, partway through the climax you learn the secrets of Halo, forging a bond you never knew existed, as you fight your way through Delta Halo and the Covenant Holy city, High Charity, awakening an ancient evil once again.

HALO 3: ODST: You play as Rookie, a new member to an elite unit known as the Orbital Drop Shock Troopers (ODST) your mission was to assault a covenant carrier above the African mega city New Mombasa but due to an unexpected new member, your priorities
due to the carrier slipspace jumping, your drop pod malfunctioned and you crash into the side of a building, knocked out for 6 hours, you wake up and are scattered from your team, you have to walk around the city to uncover clues of where your team is and what happend to them.
(Note: Even though its called Halo 3: ODST, the game takes place during the events of Halo 2)

Halo 3: Halo 3 continues right where Halo 2 left off on Master Chiefs story, The game takes place a few months near the end of the war, You play as Master Chief with a new ally by your side, You crash land on Earth, in Africa, the covenent fleet uncovered a forerunner artifact, your job is to stop Truth from activating the Ark and killing him, a portal opens up and you and a skeleton crew of USNC and friendly elites go through to follow truth to the Ark, finding the cartographer and the control room for activating the rings, you gain a unlikely ally for a short time being until they turn on you, you find out that the Ark is a installation for the manufacturing of the rings themselves. You go into the flood infested High Charity to locate Cortana to get the index to fire the newly formed ring above the Ark, to kill the local infestation of the flood.

Halo 4: Halo 4 continues off where Halo 3 finished, you're trapped on the aft end of the USNC Frigate "Forward Unto Dawn", 4 years after halo 3 finished, you wake up to find Convenant scavangers tearing apart the ship, you fend them off to find you and the ship in the proximity of the forerunner planet known as "Reqiuem" your ship gets pulled into the planet through a graviity well and you land among the wreckage, you find out that cortana is in the starting stages of rampancy, as you fight through the covenant forces on the planet, you fight an acient army known was "Promoethens"