Aren't all games basically linear?

I think use of 'linear' is like a suspension of disbelief thing-- how easy or hard it is to ignore the fact that you aren't making decisions in a medium that's got a reputation for allowing you to make, err, decisions, so as far as that goes it doesn't bug me when people say a game is linear.

I understand what you are getting at.

At the same time, when someone says they don't like a game for being linear, I think that linearity holds little weight compared to gameplay/fun/graphics/action. I think it's at the bottom of the totem pole.

or about how much the creator can do to make you ignore/not notice the linearity, zelda games at their best being a good example.

Zelda DS surprised on how much new things they could add to a basically top down game. The stylus allows for so much more original content. You can even blow into the mic to blow out torches etc.

The thing that bugs me the most about linearity is that early metroid games seem to be when the word nonlinear came about. Those games seem very linear to me.

Mass Effect is a great example of a game where the path you take through the game isn't always going to be exactly the same. The end result is pretty similar, but you might finish the game with or without some of your crew, and you might have found your way to some missions in a completely different way than you did a different time, or you might behave in a different way.

the linearity was what bothered me the most about zelda ds.

or maybe it was the linear-but-trying-not-to be aspect, which lets you flounder around until you find the new item that will let you go new places. i would put it down for a week or two and then have no idea where to go or what to do when i got back.

I think the problem is people describing linear-with-garnish games as non-linear. If you're following a path but can deviate occasionally, that's still linear. Metroid is absolutely linear. Zelda is absolutely linear. Mario Galaxy and Sunshine are both heavily linear; Mario 64 is far less so.

Morrowind is a good example of a non-linear game. Yes there's a linear plot, but you don't need to follow it at all. 90% of the game is haphazardly stumbling upon stuff. GTA is more linear but is still largely non-linear in many ways.

A problem with the term "non-linear" is that it can mean many different things. By itself it is virtually meaningless; more specification is needed.

Here's one attempt (taken from http://www.sentex.net/~datanguayh/games/Adventure_Games.html ) designed for computer adventure games:

linearity
An open challenge is one for which you have all the prerequisies (knowledge, objects, and access) to solve it.
straight: There is seldom more than one open challenge.
narrow: There are seldom more than two open challenges.
wide: There are usually several open challenges, and there are several occasions with three or more open challenges.
open: There are usually many open challenges, more than three on some occasions.
Additional qualities:
segmented: The game is a linear sequence of segments. There are several common checkpoints for all possible solutions. Each segment may have its own linearity.
branching: The game splits into mostly-independent branches. The branches can be completed in any order, and you may even be able to switch back and forth between incomplete branches, working them "in parallel".

connectivity
disconnected: Each challenge stands on its own.
minimal: There are many stand-alone challenges, but there are also a few connected challenges.
moderate: Nearly all challenges are connected, but commonly on a one-to-one basis. E.g., the gold key opens the red door, and there's no other use for the gold key.
high: The world is filled with tools and information that may be used in many ways. Several objects can be used multiple times.

What about games that have a rigid (trying to avoid "linear" here) set of problems that you have to solve in a given order, but each problem can be solved in more than one way? I'm thinking specifically of many stealth games, where you can choose to be all sneaky and not let anyone see you, or go in guns blazing and are essentially playing a very different game. Puzzle games like Portal also sometimes have multiple ways around the same obstacles. Is this non-linearity?

Games like Morrowind/Oblivion are good at doing this too. For example, do you want to sneak into the Lich's lair and pickpocket the item that gives him strength, thus killing him? Or just charge in with a huge motherfuckin ax? TBH I find this type of openness more interesting than being able to choose to do or not do a few side quests

in tenchu you had the freedom to get through each level any way you wanted; overall the game was linear (the order of the levels never changed, and the object of each level never changed) but the route and methods you took to get to the end of each level were as varied as there were players to play it