Halo: Combat Evolved (released on November 15, 2001) introduced the Halo series from relatively Humble Beginnings. Humanity has been losing a war against the Covenant for the last 27 years, and the game starts following a devastating defeat at a major Earth colony, Reach, and the crew of the warship the Pillar of Autumn. The game opens In Medias Res as the warship comes under attack, and is forced to make a crash landing on a mysterious ring-shaped Covenant-worshiped megastructure known as Halo.The player controls the Master Chief, one of the last of a group of specially raised and trained cyborg Super Soldiers: the Spartans. He is taken out of stasis during the attack on the ship, and his mission is to protect the survivors, find out what Halo is and what the Covenant want with it. Master Chief is the quiet type but the AI program "Cortana" linked into his battle suit does most of the talking and provides plenty of tech support. Together they eventually uncover an ancient threat aboard the Halo which makes the Covenant look like a church picnic. The Halo itself has a much more malevolent purpose...This First-Person Shooter was the big title used to launch the Xbox console. Its superior graphics, interesting story and engaging gameplay made it a hit with critics and gamers alike, and it was hugely influential in bringing the concept of LAN parties, which was later expanded upon with Halo 2 being the Killer App for online gaming for the Xbox. The seamless integration of vehicles, the very expansive levels and the constant rotation of weapon types gave it a unique experience.A port to Windows and Mac OS was released several years later courtesy of Gearbox Software, which added native online multiplayer without tunneling utilities, the Fuel Rod Gun (strangely treated as an energy weapon) and Flamethrower weapons for multiplayer, as well as the Banshee and a new Warthog with a rocket turret as multiplayer vehicles along with the usual computer gaming features (enhanced graphics, mods, and so forth). The original release was not particularly designed for modification, however, and so they released a separate Halo: Custom Edition with some engine optimizations, exclusively used for multiplayer. It has its own separate download and installer, but requires a CD key from the retail version as well as having a CD check.After many rumours of a remakefor its tenth anniversary, Halo: Combat Evolved Anniversary was released on November 15, 2011. The intended goal of the remake is to update the graphics, but otherwise replicate the gameplay and story exactly: the campaign mode uses the original Halo engine for gameplay with a new, toggle-able graphics layer on top. The remake's multiplayer is run out of Halo: Reach, using a set of playlists that have been balanced to replicate the feel of Combat Evolved. The disc also comes with access to the Anniversary Map Pack, a new set of Reach maps that includes fan favorites from Halo 2 and Halo PC in addition to most of the maps from Combat Evolved.
Alternate Reality Game: The Cortana Letters, while not a true ARG, served as a foreshadowing of things to come in the promotion of subsequent installments. These were a series of e-mails sent from Bungie-controlled addresses (and a couple of hidden messages on the discs of other Bungie games) to notable Marathon fandom people, authored, apparently, by an AI entity named Cortana, intent on warning humanity about an impending alien invasion. Over the course of the letters, she shared details about "the humorless war machine" she has to share processing space with, and the religious zealots "whose main form of worship takes place at the altar of orbital bombardment", as well as the "unbroken ring" whose creators have simply vanished. While many of the details revealed in this way back in 1998-1999 have since changed significantly (particularly in terms of Cortana's own characterization), the Letters gave away quite a good chunk of the game's plot.
Artificial Brilliance: The unit A.I. in Halo: Combat Evolved was quite a step up from its contemporaries, and was praised by critics as one of its best technical points. Much of the player base likewise found the challenge of "smart" enemies to be a huge appeal of the game's combat.
BFG: The Fuel Rod Cannon, especially when wielded by tiny Grunts. The weapon is unusable by the player in the Xbox version.
Body Horror: Captain Keyes suffers this from the Flood.
Book Ends: The game begins and ends on the Pillar of Autumn.
Boring but Practical: As you may learn from Jackals on Legendary, the plasma pistol is extremely useful when paired with a fast trigger finger. Semiauto fire + very short overheat + good against health AND shields = murder machine. The only gun that can compete with it for sheer damage output is the shotgun at close range. Plus you don't have to worry about chewing through batteries because it's the most common gun in the game!
Bittersweet Ending: The threat of The Flood and Halo is destroyed by the destruction of the ring. As a result, everyone on the ring was killed and Master Chief and Cortana are stuck in space, and the Covenant are still out there, headed for Earth.
Co-Op Multiplayer: If Master Chief is the lone protagonist hero of the game, who is the carbon copy Player 2 is running around as? In the Expanded Universe Novel of the Events Master Chief's fellow Blue Team member Linda is fatally injured but placed into Stasis with him.
Fanon has this as an alternate reality where Noble Sixdidn't stay behind on Reach, or (more likely, considering the identical armor) where Linda didn't receive the fatal injury..
Sadly, this mode has been removed in the PC port, presumably because it was split-screen-only and no split-screen mode was present at all.
In the Pillar of Autumn there was a terminal in the cryo bay that shows the vital signs of the Master Chief in his cryotube. In Anniversary's co-op mode there are now two terminals. The second? It identifies Linda as the inhabitant of the cryotube that the second player emerged from.
Copy And Paste Environments: The game series is based on a psuedo sandbox-style level design, with you having to traverse many locations that are basically identical in appearance. It is most noticeable in this game, which takes place entirely on Halo and you travel through several identical areas and some levels are prior levels done backwards.
Deflector Shields: Master Chief, Elites, and the more powerful Sentinels are protected by these.
Disney Death: Sergent Johnson gets Retconned into getting one. Even though, despite his fairly low screen time, Bungie did everything but show his actual death.
The Legendary ending shows him to be on the ring when it explodes. While this is non-canon, it would be very odd for a humorous non-canon ending to randomly kill off one of the few characters in the game for no apparent reason.
It was stated to be his twin brother
The Dog Bites Back: Marines do not tolerate treason - kill more than a couple of them and the rest will mutiny. And they're pretty formidable opponents, so keep them on your side.
Drives Like Crazy: "Oooh, a Warthog! That turret looks sweet, I call it!" Yeah, you'll regret that decision pretty quickly.
Exact Time to Failure: The last Warthog run through the Pillar of Autumn takes place whilst a number of nuclear reactors are in the process of undergoing a massive meltdown, followed by a huge explosion. Cortana helpfully places a very exact timer onto your HUD to show when the meltdown will occur.
Executive Meddling: The reason for the "Combat Evolved" subtitle; Microsoft was apparently worried about the game being taken as religious or something.
Fan Remake: The Halo: Custom Edition for PC allows a number of mods to be made to the single-player campaign. A CMT (custom map team) campaign has already been released with Halo 2 and Halo 3 weapons and enemies added to the game, and the CMT is currently working on a new version incorporating modern-quality graphics.
Hanging Separately: The Humans and the Covenant, despite both being attacked by the Flood, they are unwilling to help each other. In fact the Covenant will even prioritize Master Chief, even when being attacked at that moment by the Flood. Justified in that the Covenant are waging a holy war against humanity, the Chief is seen as the anti-Christ, and some new aliens aren't goin to stop them from killing some more soldiers.
Harder Than Hard: The Legendary difficulty setting. As it says ingame: "This is suicide.
Justified Tutorial: You're taught how to control your character under the pretext of a post-hypersleep examination. This is skipped entirely in co-op or on higher difficulties.
Laser Blade: Gold-armored Elites use these, and can waste you with one hit.
Law of Chromatic Superiority: Higher ranks of each enemy type are distinguished by the color of their armor. For example, red Grunts are better than orange grunts. In later games, this was modified so that higher ranking enemy types had very different-looking armor altogether.
Left the Background Music On: In one of the cut-scenes, some Marines are heading into battle while generic Heavy Metal plays. One of them asks "Why do we always have to listen to the old stuff?" and their sergeant replies that it is part of Earth's culture.
Word of God says that Bungie originally planned to license Steppenwolf's 'Magic Carpet Ride' or Rolling Stones' 'Paint It Black' for this scene, but was vetoed, resulting in the generic electric guitar.
Level In Reverse: Half the game is you moving into areas to fight the Covenant, the other half is you pulling back to escape the Flood.
Precursor Killers: The Flood. More accurately, the Forerunner killed themselves and almost all other life in the galaxy in order to stop the Flood.
Psycho Strings / Drone of Dread: Typically used in music associated with the Flood, such as Shadows (Between Beams), Suite Autumn (Suite Fall), What Once was Lost (Unfortunate Discovery), Lament for Pvt. Jenkins (Private Service), Trace Amounts (Bad Dream), Library Suite (Dewey Decimate), and Alien Corridors (Xenoarcheology). The Anniversary remastered tracks especially turn up the horror factor.
Publisher-Chosen Title: As Bungie's Jaime Griesemer explained in a retrospective Edge article, the developers didn't come up with the "Combat Evolved" part of the title:
"Microsoft marketing thought Halo was not a good name for a videogame brand. It wasn't descriptive like all the military games we were competing with. We told them Halo was the name. The compromise was they could add a subtitle. Everyone at Bungie hated it. But it turned out to be a very sticky label and has now entered the gaming lexicon… so I guess in hindsight it was a good compromise. But the real name of the game is just Halo."
Reactor Boss / Unplanned Manual Detonation: Cortana sets a counter to detonate the Pillar of Autumn's engines... and 343 Guilty Spark stops it. Master Chief then does it with rockets and grenades.
Redshirt: The ship crewmen from the first couple of levels. They have less health than even a Grunt, and are armed with pistols (if at all). They even wear red (and yellow, and orange, and blue, and on the bridge, even black) uniforms.
Redshirt Army: The UNSC Marines. Useless for almost everything except manning your Warthog's gun.
The Reveal: We have two regarding Halo's purpose. The first was that it's a containment facility designed to prevent the Flood from escaping. The second is that Halo itself is a weapon that can and has killed all sentient life within 25,000 light years.
Shout-Out: Many to Bungie's older First-Person Shooter series Marathon, to which Halo is a Spiritual Successor. As Matt Seoll (who ran Bungie PR from the Marathon era up through the first Halo title) said, "Anyone will be able to enjoy Halo, but the ones who will enjoy it the most will be the old-school fans."
Also, the "Bandanna" skull in the Anniversary release is a shout out to Metal Gear Solid, where Snake can get a bandanna that gives infinite ammo.
Sniper Pistol: The human pistol. It's the single most practical weapon in the game, with a much higher accuracy and stopping-power than the so-called "assault rifle".
Sole Survivor: You are the only human left alive who was on Halo by the end of the game. This is retconned in the novels.
Spiritual Successor: To the Marathon trilogy. Pretty much every single bit of human tech, signage or terminology (as well as the related gameplay mechanics) except for the appearance and gameplay functionality of the MJOLNIR armour was lifted wholesale from Marathon and into Halo.
Tractor Beam: The Gravity Lift that allows passage in and out of the Truth and Reconciliation.
Troubled Production: The campaign for the game, was completed in five months, due to the time scale imposed by Executive Meddling, explaining the fact that it pretty much repeats backwards from the halfway mark. To put this into perspective, the first E3 demo for Halo 2 took this long to produce.
What Could Have Been: Halo was originally slated to be an RTS on the Macintosh, later an FPS on Mac OS and Windows. The unveiling trailer was even shown at an Apple conference to demonstrate the Mac's (and Open GL's) graphical capabilities, though the game at that state looked significantly inferior to the final product. Features that did not make it to the final game, such as wildlife, were highlighted.
The co-op campaign could be counted as this, seeing as Anniversary confirms that Linda was the inhabitant of the second cryotube.
You Just Had to Say It: After you first enter the titular Covenant ship in "Truth and Reconciliation," a marine comments that there might not be any Covenant on board. Immediately after, enemy contacts show up on the motion tracker. A second marine chides the first for tempting fate.
Your Size May Vary: The Pillar of Autumn is at least four times bigger in the final set-piece then it should be, with you explicitly driving at least 3 km to reach the Longsword space fighter.
It's quite funny because in every other aspect of the game Bungie went to excruciating detail in creating the scale of the game.
Tropes relating specifically to the remake, Halo: Combat Evolved Anniversary:
Arc Number: Guilty Spark mentions offhand that the original plan was to build twelve Halo installations instead of seven...
Battle in the Center of the Mind: One terminal has Captain Keyes struggling to remember who he is and fighting off the Flood infection. By the end, the voice of the Gravemind can be heard.
Bottomless Magazines: The purpose of the Bandanna Skull. Remember all that time you kept running out of ammo during "The Library"? Now, you never lose ammo when that skull is on. And you can still get achievements with it.
Call Forward: The terminals in Anniversary details video logs kept by Guilty Spark. One in particular has him talking about how he hasn't heard from his counterpart on Installation 5 for some time, wondering if containment was breached...
Canon Welding: The terminals interconnect a lot of the other games and EU together as the series has evolved significantly since the original game. Guilty Spark narrates most of them, with references to the other Monitors and things that showed up in later games.
Continuity Nod: The terminal videos have several, including to the expanded universe.
The Keyes terminal showing Keyes and his mental struggle with Gravemind is an expanded version of a scene that was in Halo: the Flood, the novelization of the first game. A young Dr. Halsey also appears in flashbacks from Keyes' memories, and her appearance is similar to what she looks like in the Halo: Legends anime, with elements of her Reach design. His daughter also appears in this.
Linda-058 can be seen on the cryo bay status monitor next to the Chief, a nod to Halo: The Fall of Reach and Halo: First Strike.
Shot for Shot Remake: Halo: Combat Evolved Anniversary is identical in nearly every respects to the first game, the original game engine is used with a modern texturing engine overlapping it to give it new high-definition graphics and framerate. That means the game plays exactly the same (completes with a feature to toggle between the old and new graphics) and the cutscenes are similarly remastered (although, on close observation, it can be noticed that the cutscenes have been slightly modified from the original, such as character animation (most noticeable on the secret Legendary ending)). Because of that, it isn't quite up to par with contemporary next-generation graphics, it's about on par with Halo 3 from 2007.
The only actual changes is the inclusion of terminals hidden within the original levels containing videos that ties the franchise more closely together as well as potentially hinting towards the story of Halo 4, as well as unlockable skulls that can be used to modify gameplay when replaying the levels.
Shout-Out: The marine that Master Chief rescues at the life pod looks almost exactly like Marcus Fenix, the hero of Gears of War, the Xbox 360's other major exclusive shooter franchise (he's noticeably missing if you examine the bodies at the crash site in the next level).
Updated Re-release / Video Game Remake: Halo: Combat Evolved Anniversary is a bit of both. The single-player mode actually runs on the original Halo: Combat Evolved engine, but with updated graphics using resources taken from Halo: Reach. The multi-player mode, on the other hand, has been rebuilt from the ground up using the Halo: Reach engine.