What are your favorite Expansions for any game, of all time?

Diablo II LoD, Everquest Ruins Of Kunark + Scars Of Velious, Sims Hot Date + Vacation, STALKER Call Of Pripyat, Half Life 2 Episode 2, Star Wars Galaxies Jump To Lightspeed. All goodies I played through the years that actually added onto the core gameplay of the original games like a good expansion pack should.

I miss the era of expansion packs, miss me with that "dlc" or "add on" nonsense.

Yep, even when it comes to Fallout 4, the fact that Far Harbor was large enough to contain all of the necessary elements to build a cool new cohesive location, expand on playstyles, and provide a complete narrative vs how empty Nuka World and Automatron were is where I draw big inspiration.

Shadow of the Erdtree has frustrating parts, but is ultimately a prime example of an Expansion vs DLC. Same with Phantom Liberty, for the same reasons as Far Harbor.
- Oh I forgot Dark Souls Prepare To Die Edition, which added the Artorias Of The Abyss expansion pack.

Red Alert 2: Yuri's Revenge is a shining example of what an expansion can be. A lot of refined mechanics, better fleshed out factions (plus one new one!) and three new campaigns with just as many FMV cutscenes as the previous iterarion.

Honorable mention and this kinda doesn't count but Mental Omega is a mod for Yuri's Revenge that has between 3 to 4 times more content than the base game. There's a dozen subfactions split between four subfactions and inregrates features from later C&C games while introducing a lot of it's own stuff. It has some "borrowed" voice lines from other games but there are some units that have original voices which is pretty cool. No FMV video though. It's suprisingly deep for what it was based off of and it has become one of my favorite RTS experiences.

Side note:

This is such an unpopular opinion of mine but while Dead Money is cool my favorite of the FONV expansions was Old World Blues because of the goofiness of the characters contrasted with the manmade horrors of the big empty. I found Lonesome Road to be meh and Honest Hearts to be uncomfortable with how it seems to embrace the concept of the "White Man's Burden" uncritically.

This is such an unpopular opinion of mine but while Dead Money is cool my favorite of the FONV expansions was Old World Blues because of the goofiness of the characters contrasted with the manmade horrors of the big empty.

Unpopular? Thought that was the standard! Love for Dead Money was the spicy take, most fans loved OWB or LR to my knowledge.

Maybe things have changed over time, haha
Generals Zero Hour fits this as well, absolutely fantastic expansion. It was like an entirely new game.
Yuri's Revenge

Dawn of War: Winter Assault gave all the non-Space Marine factions in the base game a campaign. Sure, they were all sorta mushed together, but they got one! And also it made the Imperial Guard playable.

Dark Crusade was neat, and so was Soulstorm, but Winter Assault showed what the game could become.

just imagine living in a socialist utopia where Dawn of War Soulstorm is open source, getting regular updates like graphics updates, optimizations, native support MacOS and linux, ARM builds, new campaigns added regularly, new game modes, an optional hybrid LoL/DotA game mode...
- I mean there's a pretty lively modding scene that does almost all of that

Total Annihilation: The Core Contingency, back when an expansion pack was something you bought boxed at a store.

StarCraft: Brood War was also nice, but I always liked Total Annihilation more.

dark souls 3's the ringed city dlc is pretty perfect imo (though halflight is pretty hit or miss)

i've never cared about playing the game properly but age of mythology's titans expansion is great.

warcraft 3: the frozen throne for sure

gonna also say spore: galactic adventures for the meme

Blizzard during their golden age created nothing but bangers: Starcraft Brood War, Warcraft 3: The Frozen Throne, and Diablo 2: Lord of Destruction. They turned great games into some of the best their entire genre has to offer.

I also have a soft spot for World of Warcraft: Burning Crusade. I started WoW a couple of months after release, but I got really into it with Burning Crusade.

Additionally, Dawn of War 1 and 2 had some really fun and good expansions. Soulstorm's campaign was incredibly fun.

Gotta be The Binding of Isaac: Repentance. Took a mod that almost doubled the game's content and then added even MORE to it and over doubled the character count (technically). I take issue with some of the balance changes made after launch that feel a little no-fun-allowed but as a whole it's incredible

Dead Money good, Old World Blues good

Dark Souls I & II DLC good (DS3's DLC being kinda mid is my hot take of the day)

XCOM: Enemy Within added a lot of depth to Enemy Unknown

Dishonored: Knife of Dunwall & Brigmore Witches was more DIshonored with new gameplay features and more time with the base game's most interesting character

Hearts of Stone/Blood and Wine for The Witcher 3. I'm sorry UlyssesT but it's so goated

Ds1, 2, 3 and bloodbornes expansions were all peak.

Maybe illegal but battlefield games had some great xpacs from bf3 and before. Bad company 2 vietnam was great, i put more hours into that than the main game. Aftermath, close quarters and back to karkand were all brilliant expansions i dumped silly hours into. Endgame was poo.

Far cry 3 blood dragon was good fun. And ofc every expac for dawn of war 1.

Dark Souls II DLC trilogy was goated and some of the most interesting souls content period. except for the multiplayer boss sections. we don't talk about those.
- Burnt ivory king fight is peak. Blue smelter demon was... Well i despawned the area listening to chapo so wasn't that bad lol.
  
  Also i kept putting fume knight in phase 2 cos i was wearing velstadts armour lawl
Close Quarters for BF3 was so sweet. A couple of those small maps were incredibly well designed, and it had a great Gun Game as an official game type.
- I love how they added loads of smgs and shotguns then made maps where the destruction was small scale like demolishing office buildings. It looked so good ripping apart furniture and thin walls in a map that starts pristine.
  
  The scavenger game mode in aftermath was my favourite, all the fun of a battle royale without the tedium, trying to keep a good weapon all round was exhilarating.
  
  Oooh battlefield whatever happened.

BioShock 2: Minerva's Den

Half-Life 2: Episode Two

Halo 3 ODST

uh, the Zoo Tycoon expansion that let you have dinosaurs

Not sure if it counts as an expansion, but Kingdom Hearts 2 Final Mix: introduced critical mode difficulty. The best difficulty mode and combat in the KH series which required you to use every tool in Sora's toolkit. Absolute kino.

Monster Hunter World: Iceborne: I know it brought the controversial clutch claw mechanic, but I played gunlance and could just ignore it lol. G-rank difficulty, a bunch of QoL changes, a great roster of endgame monsters, and endless grinding mode, the Guiding Lands.

Monster Hunter Rise: Sunbreak: After the really disappointing and lacking Rise endgame, Sunbreak comes out and brings back the monster hunting in Monster Hunter. Weapon balancing, more wirebug moves, insane armor sets and abilities, armor skill customization and rerolls, fan favorite endgame monsters are back, npc followers can join you on hunts, and endless monster grinding is back. Just a complete 180 on the opinion I had on base game Rise, it saved this generation of Monster Hunter.

World of Warcraft: The Burning Crusade: got a lot of great memories playing this since this was the only expansion I was in a chill raiding guild and we got furthest progression on our server. Horde got paladins and I rerolled to Blood Elf paladin, my favorite class. Played a lot of PvP and did well in arena.

the clutch claw was annoying on a lot of weapons but holy fuck the lance clutch counter was
World of Warcraft: The Burning Crusade: got a lot of great memories playing this since this was the only expansion I was in a chill raiding guild and we got furthest progression on our server. Horde got paladins and I rerolled to Blood Elf paladin, my favorite class. Played a lot of PvP and did well in arena.

I mucked around a bit with this at launch, it was my intro to WoW. I only did a few of the dungeons as horde and played a druid. Been meaning to try out a classic private server sometime and see some of the stuff I never got to see on retail.

Mists of Pandaria for WoW, not only really great atmosphere but also introduced many crucial mechanics that improved the game immensely

Tours and Tournaments for CK3, plugged the peace boredom gap in game

Every major expansion for Civilization 4-6

Stellaris: Utopia, Megacorp (though more of a free patch that came with its release then the expansion itself), Nemesis, Machine Age

Warhammer TW2: Tomb Kings, waited for that faction since beginning of series and didn't get disappointed

Half Life: Blue Shift and Opposing Force remain all time favourites, but Far Cry: Blood Dragon and the various additions to the Binding of Isaac are also up there.

Opposing Force is awesome, a bunch of new stuff, and I enjoyed the new npcs. Too bad Blue Shift is short and Decay is a PS2 exclusive. I wish there was more HL1 expansions.

I'm a fan of all of the story expansions for Borderlands 2, but especially the D&D themed one

The Rise of the Witch King expansion for Lord of the Rings: The Battle for Middle Earth 2

If you like RTS games and/or Lord of the Rings these games are pretty easy to pirate and there is an active modding community.

Battlefield 1942 was the first FPS I got really into. Its first expansion, Road to Rome, was meh, but the second expansion, Secret Weapons of WWII, added some really unique and exciting weapons and vehicles. I especially loved flying the Goblin and the HO-229 around harassing infantry and light armor.

Looking back on it, it's pretty cringe and brainworms that they made an expansion focused around wunderwaffen weapons and a stand-in for the fucking SS. But damn if adolescent me didn't have hours of fun pew pew'ing around with a jetpack shrug-outta-hecks Don't worry I play less-overtly-fascist games now, like Helldivers II.

The Sword and Shield expansions, honestly. The base game was pretty shit, though.

Sonic 3 and Knuckles