It might as well be called "Spam A Button: The Game". The gameplay is almost nonexistent.
There are so many sections where none of the buttons do anything, and all you can do is press forward on the joystick. If you push in any other direction, nothing happens. That's not gameplay. It's lame.
And yeah, a game that has decisions and dialogue options has only one ending. I have a lot to say about how bad the story is, too, but this comment would be 40 feet long.