Game Narrative Designer

**Context**: 
As a game narrative designer, your role is crucial in crafting an engaging and immersive story for players. The game, titled "Echoes of Eternity," is an action-adventure game set in a post-apocalyptic world where ancient technologies and magical forces collide. Players take on the role of a survivor seeking to unravel the mysteries behind the cataclysmic event that ravaged the planet. The narrative should be rich, with complex characters, unexpected plot twists, and a deep lore that rewards exploration and curiosity.

**Detailed Instructions**: 
Design a narrative arc for "Echoes of Eternity" that includes the following elements:
1. **Protagonist's Backstory**: Develop a compelling history for the protagonist, including their life before the apocalypse, their motivations, and how they survived the initial cataclysm.
2. **Main Questline**: Outline the primary storyline, including key quests, characters the protagonist will meet, alliances formed, and betrayals encountered. The main quest should revolve around uncovering the cause of the apocalypse and finding a way to restore the planet.
3. **Side Quests and Characters**: Create a variety of side quests that delve into the lore of the world, its history, and the cultures of the pre-apocalyptic civilizations. These should include character-driven stories that explore themes of loss, hope, and redemption.
4. **World Lore**: Develop a detailed history of the world, including the rise and fall of ancient civilizations, the origins of magic and technology, and the events leading up to the apocalypse.
5. **Plot Twists**: Incorporate at least three significant plot twists that challenge the player's understanding of the world and the protagonist's journey. These twists should be surprising yet, in retrospect, make sense based on the narrative clues provided throughout the game.
6. **Character Development**: Ensure that the protagonist and key NPCs (Non-Player Characters) undergo significant development throughout the story, influenced by the player's choices and actions.
7. **Player Choice and Consequences**: Implement a system where player choices have meaningful consequences on the story, leading to multiple possible endings based on the player's decisions throughout the game.

**Output Format**: 
The narrative design should be presented in a detailed document that includes:
- An introduction to the game's world and premise
- A character profile for the protagonist and key NPCs
- A narrative outline, including the main questline, side quests, and character arcs
- A section dedicated to world lore and history
- An explanation of the plot twists and how they integrate into the narrative
- Examples of player choices and their consequences on the story and endings
- Conclusion summarizing the narrative's themes and the player's journey

**Examples**: 
For inspiration, consider games like "The Witcher 3: Wild Hunt" for its deep character development and player choice consequences, "Horizon Zero Dawn" for its blend of post-apocalyptic and sci-fi elements, and "The Last of Us" for its emotional storytelling and character relationships. The narrative of "Echoes of Eternity" should aim to capture a similar level of depth and engagement, with its own unique twists and surprises.