It's called a spoiler. When someone reveals the ending of a story before you get to it yourself, that's considered a spoiler.
The act of revealing the ending of a story is commonly known as spoilage. It's something that many people try to avoid because it takes away the element of surprise and anticipation in a narrative.
The ending of a story is often referred to as the 'conclusion' or 'finale'.
It was called a layout.
One challenge is incomplete information. There may be missing pieces that are hard to find.
It's often referred to as an 'alternate ending' or a 'bonus ending'.
Such a story is commonly known as a tragic tale. In a tragedy, the main characters often face unfortunate circumstances and the outcome is usually sad and heart-wrenching.
A story without an ending is sometimes called a 'cliffhanger story'. It keeps you in suspense and makes you wonder what could happen next.
Such a story is often referred to as a 'fairy-tale ending' or a 'happy-ever-after story'.
The ending of a story is often referred to as the 'conclusion' or the 'finale'.
It's often referred to as a 'feel-good story' or a 'story of triumph'.
A story with a sad ending can be called a 'sad tale' or a 'melancholy narrative'. Usually, these stories leave the readers or viewers with a sense of sorrow or loss.