Fable 2. There is pretty much nothing from the original that you need to know to figure out how the world works in the sequel.

zombflux:
What sequels can't you play without playing the first?

This more or less sums it up. I think it would be harder to find a sequel that required a play-through the original game first. Most games nowadays use the sequel to update the game system and encourage more people to play it; updating the story comes more as an after thought.

That having been said, I doubt I would enjoy the upcoming Mass Effect 2 without finishing the first one. And as rhyno said earlier, the Kingdom Hearts series is more difficult to follow without having some idea what happened the first go around.

But then, that's what wikipedia is for...

First of all, as mentioned most early era video games with sequels are easily playable without any previous games like Mario Bros, Doom, Mega Man, Sonic and so forth. Since this is not quite what I believe the intended question to be, I'll take the biggest one that hasn't been mentioned.

System Shock 2.

After that, I like the WoW suggestion, that's something I hadn't thought of so I'll put it on my list, then I'd go with Half Life 2. While some of the characters will not be familiar, I felt it stood up quite well on its own.

Oh, and if you glance slightly to the left or right of your screen for probably a couple more days, you'll see another good answer: Grand Theft Auto.

Most of the Mechwarrior games are independent of each other. There's nothing that really ties Mechwarrior 1, 2, 2 mercs, 3 and 4 together.

System Shock 2 can be played independently of System Shock, the outcomes of the last game are explained as you play through the second.

Fallout 3
Red Faction Guerrila

Assassin's Creed 2 seems like it won't require this.

Descent 2 works fine.
Doom 2 it helps, but isn't too important.
Quake 2 is totally different.
Mechwarrior 2 is totally different...

I could go on.

Devil May Cry. The previous games aren't required to understand the plot really.

halo 2

Final Fantasy? All of the stories are pretty much separate. And the Tales series. The Metroid series is good too, though you won't catch any references to the other games (not that they matter a lot)

Fallout 3, since the prequels didn't follow a set storyline.

Ph33nix:
halo 2

Oh GOD you are so right. Hell, I skipped Halo: CE, bought 2, bought 3, and later, after being bored with the both of them, bought Halo: CE. I didn't buy the first one because as Yahtzee said, it looked like it "Had been done before and BETTER." So yeah.
~Tin

The GTA Series

The Ratchet and Clank series does a good job of connecting the games' stories, while still giving only enough backstory that you can understand who these people are. I started with the second, haven't beaten it; started the third, haven't finished it either; and then got all through the fourth without feeling lost.

Daedalus1942:
Left 4 Dead 2

That's funny! I didn't know that Left 4 Dead 2 was out yet! How did you get your hands on a copy?

I'm seriously having a very, very hard time coming up with a game where you CAN'T play a sequel without playing the original. Lets see...There's the Tales of Monkey Island, but that just because all 5 games are basically 1 game separated into chapters. The Penny Arcade games to a lesser extent, but they are also pretty episodic. Half Life episodes I suppose, but again, there episodic. Umm...that's pretty much it. Most every other sequel stands by itself pretty well, but has a few inside secrets for those who have played the other games.

L4d2, I guess

letsnoobtehpwns:

Daedalus1942:
Left 4 Dead 2

That's funny! I didn't know that Left 4 Dead 2 was out yet! How did you get your hands on a copy?

For the lose. It isn't out yet, but there's a demo.

Persona 4 (I wonder if anyone...)

Grayjack72:
The Persona games. If you don't play the earlier ones, you'll just miss some references.

Doh!

Demonraiser:
Monster Hunter Freedom Unite.

pretty much any monster hunter games... they don't have much of a story but they are damn good games nonetheless

OT: hmmm pokemon works ><

Kingdom Hearts, you need knowladge of all the games for 358/2, and the first one for chain of memories, but KHII basically said TO HELL WITH THE PLOT! CONFUSING PLAYERS IS FUN!

Civilization 4, Morrowind and Oblivion, Fallout 3, SimCity 4, and just about any long-running series or series where there is no plot, just improvements on a basic gameplay paradigm like trade sims or city builders.

Pokemon, Mario, Sonic, Zelda, Metroid, and other overly milked series.
Fallout 3, Jak 2: Renegade, Kingdom Hearts 2 after Chain of Memories, Driver 76, Ace Combat, Overlord 2, Destroy All Humans 2, Final Fantasy Dissidia, God of War: Chains of Olympus, Socom Fireteam Bravo 2, Ratchet and Clank, Burnout, Star Wars Battlefront, Spiderman movie games, Jump Ultimate Stars, Spyro and Crash Bandicoot. I could name many more but I'm away from my game stash at the moment.
Also I played Metal Gear Solid 3 as my first game in the Metal Gear series and I understood the story and gameplay fairly well. Well, as much as one actually can understand any Metal Gear game before requiring a lobotomy to remove the sections of their brain that are necessary for memorization and logic.

Homeworld 2

Say what you will.

L4D2, resident evil 4, almost every Silent Hill game, and Team Fortress 2

letsnoobtehpwns:

Daedalus1942:
Left 4 Dead 2

That's funny! I didn't know that Left 4 Dead 2 was out yet! How did you get your hands on a copy?

Just fail... You know damn well I meant you won't have needed to play the first one in order to enjoy the 2nd. Also, the demo is now completely public. Ive been playing for 3 weeks prior, but it's now public.

I would have to go with the Sly Cooper series. (In fact, I started with Sly 3: Honor Among Thieves.)The major back-story and recurring characters are explained in each successive game.

siffty:
f.e.a.r 2

IDK bout that one, the first one is rather important for you to understand the second one.

But yeah lot's of games you can play without playing the first. Such as GTA, Final Fantasy, Total war games, and the dynasty warrior series. Idk those are all basically series. With direct sequels (that continue the same basic storyline) you may want to play the first one like Mass effect and Halo.

Deus Ex:Invisible War

You want to play the sequel first that way you aren't disappointed by it.

eggcarrier:

zombflux:
What sequels can't you play without playing the first?

This more or less sums it up. I think it would be harder to find a sequel that required a play-through the original game first. Most games nowadays use the sequel to update the game system and encourage more people to play it; updating the story comes more as an after thought.

That having been said, I doubt I would enjoy the upcoming Mass Effect 2 without finishing the first one. And as rhyno said earlier, the Kingdom Hearts series is more difficult to follow without having some idea what happened the first go around.

But then, that's what wikipedia is for...

I think the question would have been better posed as something like "Which games will make less sense/lessen your enjoyment if you only play the sequel", and it still really depends on how much you value story in a game. I really enjoy a good story, and it can sometimes keep me playing when the game is a bit crap, but if someone is only playing for the game part the story matters little.

I agree about Mass Effect 2, what with the whole thing about loading from your ME1 save games. I'd also say Assassin's Creed 2 (for me at least), since I loved the story and the gameplay, and hopefully the sequel will take up Desmond's story where the first left off. Which is the point where things started to go batshit crazy. I want to know about the other subjects, and the remaining assassins, and all the writing on the walls...

any fighter HL2 (excl. the episodes) FO3 and The Elder scrolls series the story between HL1 and HL2 differec so much that you can play it als FO3 differc from setting from the first two and TES has al different stories

Pretty much every sequel. There's usually a way of explaining the story for people who haven't played the previous games.

Gears 2, basically the same as 1 but with better graphics and it had a better crack at telling a story

Enzeru92:

Jaywebbs:
World or Warcraft, although it pisses some people off if you haven't at least played Warcraft 3, That is if you try talking about lore.

That's true one of my guild mates got pissed just cause i never played any of the other warcraft games. Needless to say i never healed for any of his daily heroics

I get distracted during dailies, it goes something like this "Hey Arthena, come and help kill the dragon" me "Ohhhhhhh, flower". And thats how I have switched guilds 10 times over.

Jak 2. I never played the first one, and Jak 2 is still my favourite game of all time (Although I've played the first one now ;) )

This gen`s rachet and clank and last gen`s rachet and clank