I want to start with a choice diagram, or flowchart, showing how player choices affect the game's ending.
Here's how Metal Gear Solid plays out. (Click the image for the full-sized version.)
The game has only one player choice of any consequence, so the game's plot branches in one place.
People will no doubt object that there are lots of choices to be made in Metal Gear Solid, and that's true: the gameplay itself lends itself to a variety of strategies. It won't matter how stealthy or lethal or efficient the character Solid Snake actually is, the game's outcome is actually determined by whether the player can withstand Revolver Ocelot's torture without giving in.
Now, here's a choice diagram for Castlevania: Symphony of the Night. (Click the image for the full-sized version.)
There are more choices, but not as many as in Metal Gear Solid.
Finally, here is a choice diagram for Silent Hill. (Click the image for the full-sized version.)
This is the most complicated of the three games, offering four distinct endings with multiple paths to some.
Metal Gear Solid: Meryl or Otacon?
Providing player self-determination and telling a fixed storyline may well be opposing goals. Metal Gear Solid's notably contorted plot and lengthy cut scenes indicate that Hideo Kojima, the director, wishes to tell a fixed story. Within that framework, players may make only one significant choice: whether or not to withstand Revolver Ocelot's torture and save Meryl, Solid Snake's partner, from death. If she lives, he and she escape together at game's end. Otherwise he escapes with Otacon, the scientist who created the Metal Gear.
That the player has a choice is made explicit in the game: Ocelot explains it to Snake, and therefore to the player. The game cannot continue beyond this point without the player making a decision, either through action or inaction. It is notable that the remaining part of the game, after the choice, differs in only some details. As a result, the larger story, about the destruction of the Metal Gear and battle between Solid and Liquid Snakes, changes little.
Outside of this single decision, the player is afforded extensive freedom in the gameplay itself, even though the ending of the game itself won't be altered. The game does recognize some gameplay actions in the ranking presented at game's end. For example, the game rewards the player for killing fewer enemies and healing fewer times, and creative use of the game's stealth system can achieve these and other goals.
Subsequent Metal Gear Solid games are even more simplistic: there are no branches to the storyline. In fact, one version of the rerelease of Metal Gear Solid 3: Snake Eater, called Subsistence, will include a cinema disc that allows the player to watch the game as if it were a movie.
Next time I'll address the interesting cases of Castlevania: Symphony of the Night and Silent Hill. Each offers a different balance between story and player self-determination that I want to discuss.
In the meantime, perhaps you'd just like to comment on what I've said so far.
Update: Part 2 has been posted.
One game that effectively juggled the conflicting goals of solid story versus player choice was Fallout. While the overall game followed a relatively linear story, at the end you were presented with a number of vignettes showing the results of various decisions made throughout the game. It was very satisfying seeing my decisions actually had an impact, yet it didn't require many story paths to produce. To this day it ranks as one of my favorite game endings for just that reason.
Temple of Elemental Evil has simliar vingettes. Unfortunately most of them made reference to subplots that I didn't recognize at all!
Another interesting Konami game is "Shadow of Denstiny/Memories". It has multiple endings and a unique time-travel plotline.
"Subsequent Metal Gear Solid games are even more simplistic: there are no branches to the storyline."
I'm not sure that's true so much as the various branches reconverge, correct?
I've never played Metal Gear Solid 3, but I don't recall any plot branching at all in MGS2. I never played MGS2: Substance, so that may have plot branches I wasn't aware of.
To be more precise, I'm using self-determination to mean the ability to determine how the game ends. That's probably splitting a hair.
If the game splits at some point and then rejoins to end up at the same place, then it isn't really determining anything except the sights you saw along the way to your ultimate destiny.
An example of what you're raising would be the different ways we (Ruffin and Matt) dealt with The End (sniper) from MGS3? There are others, like whether you treat a particular wound, which determines whether you see an entertaining cut-scene with Eva. Was there something in MGS2 like this? I don't recall one.
Your objection has made me stop to think about other games. In particular, what to make of Resident Evil and Resident Evil 2? You might recall that RE1 tells a slightly different story depending on whether you choose Chris or Jill. Moreover RE2 has you play through the same story from different perspectives at different times by two different characters. Does the choice of Chris or Jill in RE1 constitute a choice which changes the ending just like what happens in MGS with Meryl? Does choosing to play as Leon or Claire first in RE2 have a significant effect on the game's ending or story? I don't recall, but I'd like to look into it, and maybe think a bit more about a better way to analyze/categorize game choice structures.