* AlternativeCharacterInterpretation: A small one, but there are a few ways to interpret Tartarus's actions upon hearing [[spoiler:Arbiter and 343 Guilty Spark revealing the AwfulTruth about the Halo rings]], yet activating Installation 05 anyway:
** His fanaticism and devotion to the Covenant religion are such that nothing will deter him, not even these sudden revelations about what he's about to do. It could be that he even believes that it is [[spoiler:''Arbiter and Spark'']] who are telling lies, not the Prophets, and that they are merely attempting to make him stray from the path and postpone the inevitable.
** Based on his initial reaction when told the truth, he seems to have a very momentary crisis of faith, as if he is struggling to process what he has been told, versus everything he'd previously been led to believe. The way he seems to quickly shake it off could be a result of the first interpretation, but could also be that he is in denial, and he keeps up the act in order to cope, and push himself forward to fulfill his duty.
** And finally, he may simply have decided that he's come too far to turn back now, and that the only thing to do is follow through on what he was sent to do, even if it's all in the name of a big lie.
* AssPull:
** Sergeant Johnson showing up alive and well despite the ending of the first game making it quite clear that no one other than 117 and Cortana survived the Halo's destruction. It only gets explained in ''Literature/HaloFirstStrike'' how Johnson got off the ring in time. It's lampshaded as early as the tutorial, where the Master Gunnery Sergeant outright asks how exactly Johnson got home, only for Johnson to claim that it's "classified".
** The Prophet of Regret somehow jumping to another Halo Ring. While supplementary material has explained how he found it, it wasn't until a decade after the game came out that an explanation was finally given.
** In Amber Clad spreading the Flood to High Charity. Developer comments have clarified that the Flood infected it while Keyes and Johnson were in the Library, and it made a pinpoint slipspace jump to the inside of High Charity to use Pelicans to maximize the spread. Nonetheless, this is never shown in-game (we never even see Flood take In Amber Clad), nor is it explained exactly how this happened (especially as pinpoint slipspace jumps are beyond typical UNSC technology, and High Charity is incredibly well-defended).
* AntiClimaxBoss:
** In the Prophet of Regret's boss fight, it's entirely possible to just run up to his chair, avoiding his easily dodged lasers, and punch him to death. At least on Normal or Easy. Trying this on Heroic or Legendary ''will'' probably get you shot to death by his dual-Plasma-Rifle-wielding [[EliteMooks Elites]] either before or after you "mount" his chair. Still, since the punching animation gives invincibility frames, it's still a viable (and silly, and still nonetheless difficult) tactic to mount his chair and punch him up to ''twenty times total'' (therefore at least five mounts, running away before and afterward since the Master Chief hops off the Prophet's chair after the fourth consecutive punch) on Legendary Co-op, since the alternative is wiping out his waves of respawning enemies almost endlessly to lower his shield.
** Tartarus could end up like this, as well. On the two lowest difficulties, it's possible for Johnson to snipe off Tartarus' shield right off the bat, which can result in the player killing the FinalBoss only a few seconds into the fight.
* SugarWiki/AwesomeMusic: [[https://www.youtube.com/watch?v=2O9K7E3lDRU "Halo Theme Mjolnir Mix"]]: take the original theme and make it even more awesome by adding ELECTRIC GUITARS!
* BaseBreakingCharacter:
** Originally, fans either loved the Arbiter and thought his perspective of the Covenant War brought a refreshing light to the Elites, or hated him due to the fact that you were suddenly playing as the enemy and not the Master Chief, without any hints that this would happen pre-release. It also didn't help that the Arbiter's levels either involved him fighting the Flood or the Brutes, both difficult enemies to battle. Demoting him to the 2P character in ''VideoGame/Halo3''[='=]s co-op initially only widened this status by triggering fights between those who were relieved Master Chief was back in the spotlight and those who wanted more of him. With time, the controversy about hiding the Arbiter as a player character faded and he became popular in his own right - in fact, his appearance in ''VideoGame/Halo5Guardians'' was met with near-universal approval by the fanbase, to the point where he became a GuestFighter in ''VideoGame/KillerInstinct'' (''KI''[='s=] Arbiter is officially a CompositeCharacter, but he was clearly based mainly on this one).
** The Gravemind: menacing and creepily intelligent monster who's a sinister antagonist and even more interesting temporary ally, who adds an interesting wrinkle to the game's plot, or goofy plant monster who spouts philosophical drivel and has no place in the Halo universe? As with the Arbiter, the naysayers have largely grown less negative with time, with fans noting his interesting personality and multiple memorable quotes. His [[ArtEvolution drastically different]] (and [[BodyHorror far scarier]]) redesign in the Anniversary addition [[AuthorsSavingThrow helped a lot.]]
* BestLevelEver: Metropolis. Drive a Scorpion tank across a bridge fighting Ghosts, Wraiths, Banshees, and Phantoms, followed by a battle in the city after a quick battle in a tunnel, and the level ends with the [[BestBossEver Scarab fight]].
* BigLippedAlligatorMoment: The meeting with the Gravemind. Master Chief and the Arbiter just end up talking to a giant creature that looks out of place, comes out of no where, and never mention it again in the game. When the game first came out, a number of players were confused what the thing was, having no idea it was actually something of a secret antagonist and the being behind the Flood in this game due to looking like some kind of plant monster. Part of this was because the original design (BodyOfBodies) and the level meant to set it up (Forerunner Tank) were either not used or were cut, so it just happens.
* BreatherLevel:
** After the level "The Oracle", which introduces the Flood, the player is thrust back into the boots of the Master Chief in the next level, "Delta Halo".
** Sandwiched between two [[ThatOneLevel difficult]] levels in "Regret" and "Quarantine Zone" is "Sacred Icon", of which the only enemies you'll be encountering in the first half are Sentinels. Even when the Flood appear, the game is generous with dropping Sentinel Beams and other effective weapons for combating them, while they ([[ShotgunsAreJustBetter mostly]]) have yet to acquire the weapons that would make "Quarantine Zone" so brutal.
* ContestedSequel: While ''Halo 2'' is often considered [[EvenBetterSequel the peak of the franchise]], revolutionizing Xbox Live while crafting a more in-depth look at the Covenant and expanding on ''Halo's'' mythos and mechanics, it was never without its detractors. While it's praised heavily for its musically-diverse soundtrack, visuals, and for being a staple on the online console experience, the game was, and still is, criticized for its rushed development, cliffhanger ending, its never released E3 Demo that [[NeverTrustATrailer bore little resemblence to the final product]], and its unbalanced gameplay, both from its weapon sandbox, and the A.I. in the harder difficulty settings.
* DemonicSpiders: '''JACKAL SNIPERS'''. Sharpshooters armed with [[EnergyWeapon Beam Rifles]]. Somewhat annoying on [[GoddamnedBats Heroic and lower]], [[TheComputerIsACheatingBastard highly accurate]] and are capable of [[OneHitKO one-shotting]] a ''Spartan'', on [[HarderThanHard Legendary]], appearing in random numbers in random locations, and there are just so freaking many of them. Bungie ended up [[AuthorsSavingThrow nerfing them]] in ''Halo 3'' by adding a headlight so you can spot them more easily, programmed them so they took more than half a second to shoot you, and giving most of them carbines instead of beam rifles (which deal way less damage), with those wielding Beam Rifles showing up in set locations in far fewer numbers.
* GameBreaker:
** Though not supposed to be something that players have access to, the [[FanNickname Scarab Gun]] makes the level it can be found on completely trivial. This goes even further with the Scarab Skull in ''Anniversary'', which turns every weapon in the player's hand into a Scarab Gun, making Legendary a breeze.
** [[BottomlessMagazines The Bandanna Skull]] from Combat Evolved Anniversary makes a triumphant return in ''Anniversary''.
** There are several areas in the game where SequenceBreaking can allow the player to bring a vehicle into a section of the level where it isn't meant to go. Most notable, if a banshee's wings are blown off just before entering the final level's control room, players can wedge the thing through the door and turn the FinalBoss fight with Tartarus into an utter CurbStompBattle.
* GenreTurningPoint:
** ''Halo 2'' legitimized console online multiplayer and innovated online multiplayer as a whole, with matchmaking, lobbies, and clans becoming mainstays of multiplayer games since.
** ''Halo 2'''s marketing campaign also saw the advent of games being treated like blockbuster films, with the industry becoming more respected and profitable as a result of the game's massively successful release.
* HarsherInHindsight:
** One of Johnson's battle quotes is "In ''Halo 4'', I get a woman." [[spoiler: Johnson dies in ''Halo 3'']].
** [[spoiler:One of Cortana's line in the mission Delta Halo, "If I were a megalomaniac - and I'm ''not''...", takes on new significance with the main reveal in ''VideoGame/Halo5Guardians''.]]
** Killing the heretic Leader (Sesa 'Refumee) becomes more tragic in the Anniversary edition with the added terminals revealing how much Sesa respected Thel 'Vadamee and trusted he would do what is right had he not been fooled by the Prophets.
* ItWasHisSled:
** The player gets to play as an Elite.
** The Brutes become the central villains of the game after the Covenant splinters apart.
* ItsHardSoItSucks: One of the bigger complaints thrown at the game is that its higher difficulties, Legendary especially, go beyond offering a solid challenge and arrive into frustratingly near-impossible territory. This is largely because the Chief and the Arbiter [[GlassCannon have very little health this time]], while on Legendary, enemies are both capable of tanking damage and unleashing a torrent of unrelenting suppressive fire at you, [[TheComputerIsACheatingBastard without having to worry about overheating or reloading]]. There are fans who enjoy this brutal difficulty, especially with the rise of NintendoHard games built around trial and error in the decade after the release of ''Halo 2'', but that difficulty is reserved for those games because they're [[PlatformGame platformers]]. The transition isn't as smooth on a modern FirstPersonShooter — which is a sticking point for most players.
* MemeticBadass: The jackal snipers on Legendary difficulty.
* MemeticMutation: Several phrases have become memetic on their own, sometimes found attached to [[ImageMacro image macros]].
** "When you first saw Halo, were you blinded by its majesty? Blinded? Paralyzed? Dumbstruck?"
** "For a brick, he flew pretty good."
** "Regret, Regret, Regret."
** "Even on my knees, I do not belong in their presence."
** "Sir, finishing this fight."
** "Your ignorance already destroyed one of the sacred rings, Demon. It shall not harm another."
** Extremely Resilient, which is used to parody how easy it is to die on Halo 2 Legendary despite the Chief getting new armor.
* NightmareFuel: The Gravemind's redesign in the Anniversary edition. Gone is the plant monster of the original, say hello to a [[EldritchAbomination gigantic arthropodal atrocity]] with the texture of [[BodyHorror rotting corpses]], and a giant fanged maw nestled inside a mouth of [[{{Squick}} bloody flesh]]. Truly a thing worthy of the quote, "I am a monument to all your sins."
* NintendoHard: ''Halo 2'' is ''universally'' regarded as the toughest campaign to beat on Legendary (and it's no slouch on Heroic, either, compared to the other games in the series), with ''VideoGame/Halo5Guardians'' coming a very close second, and ''Halo 1'' coming in at third. Reasons why:
** Player shields for some baffling reason are insanely weak, and tend to go down in one hit. Another hit kills you. Coupled with the fact that enemies tend to fire from multiple directions and much faster, this means it is very difficult to attack multiple enemies head-on without having to retreat constantly.
** In Co-Op, the Iron skull is turned on automatically and ''cannot'' be turned off. If one player dies, both get booted back to the last checkpoint.
** Drones. Absolutely annoying on lower difficulties due to their swarm tactics and ability to fly about the level, here they are just insane. 15-20 Drones flying about, each firing a Plasma Pistol that will take shields down almost instantly. Have fun.
** Jackals wielding Beam Rifles (of which there are loads and loads in several levels, with "Metropolis" and "Regret" being notable examples) can kill the player in one hit, regardless of hit location. They also have insane accuracy, almost-never missing their shots. Unless you know exactly where they are, you will die. '''A lot'''.
** Brutes, once they become the mainstay enemies after the level "Gravemind", are insanely resilient, which coupled with their tendency to go berserk makes them difficult to deal with, especially if all the player has is Covenant plasma weaponry. Their tendency to carry Brute Shots which can absolutely shred the player's shields with splash damage doesn't help.
** Several levels force the player to use only Covenant weaponry, which makes them less than ideal for fighting the Flood or Brutes, the former being weak to human weaponry and the latter being incredibly resistant to plasma.
** Friendly AI is absolutely brain-dead when driving vehicles, more often than not driving the player directly into combat and then stopping, leaving the player to get annihilated.
* PortingDisaster: ''Halo 2 Vista'', which likely killed the idea of ''Halo'' games receiving PC ports for well over a decade. For starters, the PC version forces people to use Windows Vista or later to play it by checking to see if you have [=DirectX=] 10 installed, even though it was designed for the original Xbox, which uses [=DirectX=] '''''8.1'''''. A hack soon popped up that disabled this check, and it proved to work just fine on XP. Other problems include that many keys are hardcoded to be bound to Games for Windows Live (screwing anybody who prefers a non-WASD keymap), network connectivity was patchy (GFWL again), and the modding toolset was crap (basically impossible to create new single-player content). The game is also not future-proof, as it does not support resolutions over 1080p nor frame-rates above 60 Hz (while the original ''Halo: Combat Evolved'' can be run at 4K at 120hz outside of a confined vertical FOV with animations, effects, and in-engine cinematics locked at 30 FPS).
** Thankfully, all of these issues were resolved with the ''Master Chief Collection''[='=]s PC release, which supports up to 4K at 240 FPS, only requires a one-time sign-in with a Microsoft account, and has full modding tools (though 343 has warned that they were effectively developer tools and were provided more or less as-is). A later update to the game restored many of the graphical effects that had been lost in the original PC port.
* ScrappyMechanic:
** The rank system itself was surely (and ironically) the least secure aspect of ranked playlists; de-ranking was a notorious glitch in the system or result of a really skilled hacker. God bless the heart if anything more than twelve rank levels have disappeared off your record.
** On the original Xbox version, playing the game in 16:9 mode will force vertical split-screen when playing two-player locally, severely limiting the field of view and making it hard to play. Going to the console dashboard and setting the console to 4:3 will allow for the standard horizonal split-screen, and ''VideoGame/Halo3'' fixes this by having horizontal split-screen but adding black bars on the left and right sides of the screen in 2-player. ''The Master Chief Collection'' version of the game also has horizontal split-screen without letterboxing.
* SurprisinglyImprovedSequel: Not the original game, but rather ''Anniversary''. ''Combat Evolved Anniversary'' was criticised for its heavy use of PropRecycling that clashed heavily with the original look of the game, with it being clear that the developers were simply not given enough time to give the game a thorough remaster. ''2: Anniversary'', which was handled by the same developer, is seen as a huge improvement thanks to giving the game a massive graphical upgrade while still remaining loyal to the classic art-style.
* TheyChangedItNowItSucks: Fans of the original weren't happy with the Mausoleum fight in "Gravemind" changing to music from the instrumental of Music/BreakingBenjamin's "Blow Me Away" to more generic riffs in the remastered edition, presumably due to licensing issues. Fortunately, changing the graphics back to classic also changes the music back - which, of course, debunks the "rights issues" thing entirely[[note]]Although it's possible that Microsoft had the rights to the recording but not the composition, in which case they could re-use the track as-is from the original but not create a new arrangement or recording of it for the remaster.[[/note]]. They did the same with the rest of the licensed music, including all four Movements of the Odyssey that Music/{{Incubus}} wrote for the game. However, [[UnintentionalPeriodPiece both bands also scream "2004"]], so it may have been an ill-advised attempt to remove a "dated" element.
* TheyWastedAPerfectlyGoodPlot:
** The fact that there were some Hunters that sided with the Arbiter to rebel against the Prophets and the Brutes. It ends up coming off more like a BigLippedAlligatorMoment, because when one plays through the game series, the player will realize that this ends up only ever occurring near the end of ''Halo 2'', but man did it give off a cool feeling fighting alongside those all-powerful [[BossInMookClothing Bosses in Mook Clothing]] for once.
** The Covenant taking their war against humanity to Earth. Despite having tons of potential, it all ended up being crammed into just the first 3 levels of the game.
* UnintentionalUncannyValley: In the remastered cutscenes, the Prophets have teeth that look very human. The effect is remarkably unsettling.
* UnderusedGameMechanic:
** The game made non-playable allies able to drive vehicles, when previously only human players could take the wheel. The multitude of internet videos of [=NPCs=] failing miserably to drive anywhere, not crash, or not kill any of their own allies shows just how useful allowing that was.
** The Spectre was introduced in this game as basically a Covenant version of the Warthog. It only appears in three levels of the campaign, and each time your ability to actually use it is hampered. In ''Quarantine Zone'', you pretty much have to drive it, as your allies will make no effort to avoid the Sentinel Enforcers' vehicle-crushing attack, practically guaranteeing you won't get past the first platform unless you're ''very'' quick to kill those things when they spawn in. In ''Uprising'', you have to hijack it from the Brutes using it, which is easier said than done on higher difficulties. And then in ''The Great Journey'', your other option is a ''Wraith'', against whom the Spectre's only advantages are being faster and not needing to face its target. It was then replaced with the Prowler in ''VideoGame/Halo3'', never to be seen in the main series again.
** The missed opportunity to flip the series' formula on its head and have you fight Marines as the Arbiter; beyond a brief tease of the idea in Sacred Icon (in which you can encounter a group of hostile Marines that very quickly get overwhelmed by the Flood), this never happens.
* VindicatedByHistory:
** Reception to ''Halo 2'' upon release was polarizing, and Bungie themselves admitted their dissatisfaction with the final product, which had tons of great features cut and many rough edges to the levels and AI. Despite this, ''Halo 2'' managed to gain a loyal following for its efforts at a deeper story and very fun multiplayer, to the point that [[https://www.bungie.net/en/Forum/Post/2139032/0/0 a faithful few managed to keep]] its Live servers active for almost a full month after its scheduled shutdown. Since then, ''Halo 2'' getting a 10th anniversary rerelease was met with cheers all across the fandom, and Bungie veterans Joe Staten and David Candland have admitted that, despite its very TroubledProduction, it is the game they're the proudest of in the end.
** As noted in the Base Breaker section, the passage of time has made the Arbiter himself far more popular, with his appearances in post-''Halo 4'' media almost universally well-received, particularly after ''{{VideoGame/Halo 4}}'' had alienated some by making the Elites bad guys again.
** ''Halo 2: Anniversary'' also got more love with time. At launch, it was overshadowed by the poor state of ''The Master Chief Collection'' as a whole, and was generally overlooked. The fixing of the MCC's issues with time, plus the release of the game on PC gave more recognition to the excellent remastering work on offer, and now it's not uncommon to find people who prefer ''Anniversary'' over the classic game.
* SugarWiki/VisualEffectsOfAwesome: The ''Anniversary'' edition ''definitely'' qualifies as such. The original Xbox version is no slouch either, having some of the best (if not ''the'' best) graphics on the console - and they're actually toned down from the original graphics engine, which Bungie spent half the development time working on only to scrap it because the original Xbox wouldn't have been able to handle it.
* {{Woolseyism}}: In the Spanish dub, the Arbiter receives a DubNameChange to 'Inquisidor'. This works out quite well, as the more literal translation of 'Arbiter' ('Árbitro') is generally associated with sports referees rather than someone who does legal or other forms of arbitration.