In Mass Effect 3 you can choose to play campaign in Story, Action or RPG mode.
I know the difference between them is that Story focuses on plot while ignoring FPS elements; Action removes dialogue options and is focused on FPS elements; and RPG focuses on both plot and action aspects of the game.
My question would be - beyond things I mentioned above, is the game customized in any other way (by selecting one of them and not others)? Is there any possible ending "locked" in a certain mode?
Because Action Mode is the only mode that automatically chooses your dialogue options, you will be unable to direct the story to your personal narrative and will be locked to the ending that the automatic choices lead you to.
Now, if you've imported a save or play multiplayer, your previous choices will still affect Galactic Readiness and the Mass Effect Universe you play in.
No one has confirmed if Action Mode chooses identical dialogue choices each playthrough, but Action mode is the only mode where you cannot choose how you end the game.
Currently the Action Mode dialogue randomness question is being discussed here: Are Action Mode responses random?
Action mode presumably only offers you the chance at 'one' ending, since you don't get to make any choices.
The ending of Action mode is still influenced by factors like Galactic Readiness (which can be influenced not just by choices in game, but by things like multiplayer participation), and choices made in an imported saved game.
Story and RPG mode have identical endings availiable. The only difference between the two is the difficulty of combat.
