DYNASTY WARRIORS: ORIGINS

At a certain point in the story, you must choose a faction you want to side with; the game will make it very clear when you have to make a decision and are passing the point of no return. The faction you choose, and how you play specific mission(s) later on will determine which of the six different endings you will receive. Note that while this achievement is for one ending, and there are five others to get, you DO NOT need to make a new game to get the rest of the endings! Once you complete the entire story once, you get the option to go back and replay story missions, and even replay the game from any chapters, while keeping all the weapons, skills and any other unlocks you've earned (it's essentially New Game+). This means you'll be able to go back and get all six endings, all on the same save file, so don't worry about that.

How to complete the Wu story (minor story spoilers; I will be vague but still informative):