What the subject says.. In this thread I am going to discuss linearity and nonlinearity. I am going to list the pros and cons of  both of them. I am  also going to name some games as well to make my examples stronger.

        Linearity- Linear games are the video games where you are given a straight path and an objective to complete. The exploration  aspect is  either limited or doesn't exist.  Games in this category include every Call of Duty game since Modern Warfare, the Uncharted franchise, the God of War franchise, the original Super Mario Bros, Resident Evil 1-4*, Resident Evil 5 and 6, Sonic 1-3 and Knuckles* and many others.

             *= The game is mainly  linear, but there is some room for exploration and/ or the levels in said game can be finished in different ways. Sonic 3 is a good example.   You are given a straight path ( Angel Island- Hydrocity- Marble Garden, etc..), but you can finish the acts however you want.

            In  franchises like Uncharted and Call of Duty,  linearity is used to put a stronger focus on the story aspect of the game rather than the exploration aspect. In Call of Duty 4 for example, memorable moments like the nuclear explosion happened because the devs made the game like it. The memorable moments and setpieces were possible thanks to the linear aspect of the game.

            However, there are also "on-rails" games or some games that are  on rails for wrong reasons.  The early  Star Fox games are  well-known on-rails games.  They are pretty fun games even if they  limit the player mostly because  shooting enemies  can be so fun that you forget most of the time that the games are pretty linear.

           Then we have games the games that are on rails for wrong reasons. The first example is the Sonic franchise. I already mentioned mentioned how the Genesis Sonic games are mainly linear, but still offer exploration for those who want it. Well, in 2007 we got Sonic and the Secret Rings for the Wii. It was the first on-rails Sonic game ever.. The majority thought the game sucked mostly because the game  simply limited the player too much both controls and level design wise.  Combine that with the tacked on motion controls and the result wasn't pretty. Sonic and the Black Knight was the same deal, only much worse.

          Then we have Final Fantasy XIII which is called by a lot of people " Final Hallway XIII". Some people even said that it created a new genre " On-rails RPG".. That game was almost  on-rails for pretty much no reason. The last FF game before that which was XII, was pretty open, so there was no reason for XIII to be that linear. It didn't help the story at all since the story was a confusing mess. This is when linearity is a bad thing. When it  is introduced in a franchise that wasn't known for linear level design ( * cough Metroid Other M * cough*) and when it does nothing good to said franchise.

          Now, you could say that  the Final Fantasy franchise since VII wasn't really known for being very open, but they never went to XIII's level of linearity. Not even X was that linear.

       Nonlinearity- Nonlinear games are the video games where the player is able to take different paths and complete the objectives however he/she wants.  Games in this category include every GTA game since GTAIII, most of the Metroid games, Super Mario 64*,  the original Zelda, A Link to the Past, Xenoblade, etc.. In these games the focus on the story is minimal since the player can simply do extra stuff and not really care about the main story. A good example is Grand Theft Auto. There are many extra things to do if you don't really care about going any further in the story.

     *= In Super Mario 64 you have to do most of the levels in a certain order since most doors open only after you got a certain number of stars, but if you know the locations of the stars then most of the time you can just go for star number 5 instead of star number 2 in many levels. In Mario 64 there are also secrets that don't affect the main game in any way. There are there for the gamer that wants to discover as much as possible.

       Some early examples of nonlinear games include the original Zelda which simply leaves you in the middle of nowhere and you have to found your way out. The first dungeons can be completed in  any order, but after that you need certain items which you need to find on your own. The next one is Metroid which again leaves  you in the middle of nowhere. Then we have the original Mega Man which  gives you all the stages from the get-go and you can complete them in any order you want.

       However, nonlinear games also have their faults. Not as bad as linear games, but still. For example,  when a game is very open, but there is nothing to do there. The game is simply very empty. As much as I love Wind Waker, I have to admit that most of the ocean is simply empty and there is nothing to do there. Same can be said about Skyward Sword even if the game is linear. The sky is very empty and there is nothing to do. The ultimate offender though is Skyrim. The game is very open world, but the game can be so empty at times. I've heard this is probably because of the PS3 and 360 limitations, but still!

       Now I am done....... Feel free to leave your thoughts.

       
       

Well it depends what you are looking for, I love some Zelda/Metroid type exploration games, the most recent I liked in that style was Far Cray 3, and I never got to try Skyrim... as for Zelda, after the Ocarina of time I think they all stink in some way...

As for linear games, they need some very good play mecanics and a good story (if the story is no good, they should remove it as much as possible and put more efforts on the action, etc.) a game like Far Cry 3 does not make The Last of Us any worse, they complement each other, both have re-play-ability and allow for different ways to be completed, both offer a nice story and some secrets to find.

Basically, over time I have become impartial to this, I find that whether a game is linear or not does not change my level of enjoyment of it at all, what brings me in is the sense of adventure and that can be achieved in many ways... a bad open world game gets boring really fast and an overly linear game feels repetitive very fast (especially if the game play lacks depth).

Both types have their place and there are games that are heavy one way or another that I love. If I had to pin down my favorites, though, it would be somewhat open games that have a linear and engaging storyline that you can participate in when you so desire. Fallout 3/NV and Dragon Age O/2 are good example. Love those franchises to pieces and both are among the few on my "Day One" list. Games like Valkyria Chronicles and Final Fantasy Tactics also quality, as you can have battles over and over before you decide to push forward with the story.

"Now, you could say that the Final Fantasy franchise since VII wasn't really known for being very open, but they never went to XIII's level of linearity."

That line kind of puzzles me, though. FF VII was one of the most linear RPGs I've ever played and also one of the most popular. In all honesty, a lot of RPGs were highly linear, they just masked it with the illusion of choice. You might have a maze-style dungeon but there is still one entrance and one exit. Towns might be open but there is nothing to do until certain events are triggered. I do agree that people don't want new and different with Final Fantasy, though; they mainly just want a FF VII rehash. As most of the people who play Final Fantasy aren't RPG fans, it's better to just give them what they want and rake in the dollars.

Well if you truly love open world games then you will find something to do. The freedom to create fun out of nothing. For example in AC you can jump around on the rooftops for hours and try to discover every corner of the city or just have fun slaying all those useless NPCs. This freedom is missing in linear game where the only fun you can have is maybe backtracking a corridor that is maybe filled with the same enemies you just defeated.

The only bad thing in a non-linear game is that the immersion and story is suffering because of your free actions. For example if there is an urgent mission you can just ignore it for hours.

Something of a shallow analysis, but touches on most of the significant factors. In the end, linearity is more relevant to a game's narrative than its mechanics.

Final Fantasy XIII is definitely an example of linear design, but it was the lack of significant freedom in the mechanics that was more to the game's detriment. A non-linear game with similar mechanics would likely have been just as insufferable.

I enjoy non linear games but some might as well not include a story line. By the time I feel like doing another story mission I have no clue anymore what it was about. Worst offenders are AC4, Skyrim, Saints row. (Is there a story in Saints row? I can't remember)
Some progression through the world is needed, like the Fallout series, RDR, Ni No Kuni and best example Dark Souls. Or a mix between linear and non-linear gameplay, like Deus Ex: HR or The Witcher 2.

For a strong story you better stick to linear progression. Which doesn't mean it can't have open level design and exploration, The last of us did a great job at giving you freedom on a tightly controlled narrative path. Plus it's also nice to know you'll be rewarded with a new area instead of retreating familiar ground.

Actually thinking about linear and non-linear games it occurs to me that a lot of linear games have better non linear ways of dealing with objectives then missions in so called non linear games. AC4 story missions are about as on rails as you can get.

As a whole, I prefer linear games done right to nonlinear games. A nonlinear game simply can't hold tension the way a linear game can because the world distracts from the main plot. It's the classic "Link, why are you cutting grass when Ganon just kidnapped Zelda?" bit.

Final Fantasy is probably the best example of linearity done well and poorly. In XIII, most of the game is a corridor. This is APOCALYPTICALLY bad level design because there's no break from the monotony. I understand what they were going for because the characters are under pressure to flee, but the player never feels this pressure from the gameplay.

Compare this with VIII. Final Fantasy VIII's first disk is one of the best examples of linear game design ever. The first major stretch of the game is about introducing the Balamb and Balamb Garden, A bit of exploration is acceptable because there's not much tension. Squall literally has all day, so taking a break to play cards or poke around campus makes perfect sense. The Fire Cave has no branches, but it doesn't take long and it's under a time limit.

Then there's the Dollet sequence. All you do is run through town to the comm tower and run back to the ship, but you're not going to notice that because on the way out Seifer is being himself and on the way back you're being chased by a murderous robot. Oh, and there's another time limit.

This is the essence of game design. When the plot is relaxed it gives the player time to enjoy it at their own pace, even if the world at this point is quite limited. When the plot wants to be tense, though, the game design reflects it by giving them a narrow corridor and gameplay reasons to run through them quickly.

And I should point out that it's reasonably unlikely the player will see a game over in any of this, so the tension is all an illusion. The X-ATM092 is easily three times harder than even the bosses you've fought thus far, intending to push the player into running. Again, this makes perfect sense from a plot standpoint as well as for game design. It's a tutorial phase to get the player into the game, but it's also Squall's first time on the field. Squall was a rookie who was understandably nervous his first time in combat, but in retrospect he was very well prepared.

The problem is that most non-linear games defeat their own purpose; they (often) present a large free roam world with too few things to do and almost no variation, side quests are almost almost incredibly boring. Another problem is that they often invite to a loss of focus.
Linear games can be incredible, Half-Life 2 and episodes are textbook examples of how one can use linear, well-scripted design to its full advantage.

That said; a well made non-linear game can be awesome, The Witcher 3 is my most anticipated title for the 8th gen so far.

Linearity > non-linearity for me.

Better to move through a well paced, tightly constructed course than spend most of the time wandering around bored, wondering where the fuck to go.

With most of today's non-linear games I'd say at the core they actually are linear, just with an open world level selection tool.

Take AC4 for example. It's non-linear, until you start a quest. The player is constricted just like in Uncharted or GOW until that quest is either finished or abandoned. The true non-linear aspects of the game are when the player is just roaming free throughout the map. I loved sailing the seas and destroying ships as I pleased, but it felt like a distraction until I became board and did another mission.