Dark Souls. Has anyone here played that bastard? It's a non-linear game. When you start the game, you can go to pretty much anywhere, except for some places that need some kind of key, heh (plot). You can kill any NPC. You can customize your character to your liking and equip anything (this of course resulting in experienced people sticking to the "best method", like when in an RPG you have like 30 magics and you select the best one over and over -Meteor!-). And they try to hold your hand as LITTLE as possible, ending in you inevitably dying over and over.
Thing with non-linearity is that it doesn't has anything to do with the impact and extra endings. It's about breaking the "A to B" paradigm, making it instead A to either B, C, D, E, F... then at some point Z. Or finally end up with W, X, Y as possible endings.
Then the games that just throw a different cinematic depending on your variable values. Bools and integers determining what ending sequence plays (?).
Now let's think about linear vs. non-linear. Which is easier to develop? Which pleases most audiences without that much hazzle? Linear games. A lot of people are just caring for a story and blah. I'm not in that boat because I like a little more of non-linearity, but if I can please people with the easiest path, then it's a good thing to consider. Nowadays is pretty hard to achieve a good replay value if your game's main aspect is story.
If you go for a non-linear approach, there is this thing that involves branching. Let's say you make a branching, you have two results. Each of these branches then break again in two separate branches each. Now we have 4 paths. Let's say this happens over and over. With 7 levels of branching, you have 2^7=128 different paths. So you pretty much have to make 128 games in one.
Of course, I'm not taking into account that some branches start at mid of game, neither am I considering that some branches can join at some point, which is the key for branching stories, because neither you or your players will follow up with that gigantic schema where they are.
Thing with non-linearity is that it doesn't has anything to do with the impact and extra endings. It's about breaking the "A to B" paradigm, making it instead A to either B, C, D, E, F... then at some point Z. Or finally end up with W, X, Y as possible endings.
Then the games that just throw a different cinematic depending on your variable values. Bools and integers determining what ending sequence plays (?).
Now let's think about linear vs. non-linear. Which is easier to develop? Which pleases most audiences without that much hazzle? Linear games. A lot of people are just caring for a story and blah. I'm not in that boat because I like a little more of non-linearity, but if I can please people with the easiest path, then it's a good thing to consider. Nowadays is pretty hard to achieve a good replay value if your game's main aspect is story.
If you go for a non-linear approach, there is this thing that involves branching. Let's say you make a branching, you have two results. Each of these branches then break again in two separate branches each. Now we have 4 paths. Let's say this happens over and over. With 7 levels of branching, you have 2^7=128 different paths. So you pretty much have to make 128 games in one.
Of course, I'm not taking into account that some branches start at mid of game, neither am I considering that some branches can join at some point, which is the key for branching stories, because neither you or your players will follow up with that gigantic schema where they are.
. Also I like to make some scripting, like my first attempt in the AGS (a status window and some stats formulas, simple for us starters 
).