Metroid: Zero Mission features multiple unlockable endings and a special image gallery, encouraging replayability. The ending you receive is determined by your completion time and item collection percentage. Generally, faster times and higher item percentages lead to better, more revealing endings, often showcasing Samus in different poses or without her helmet.
- Completion Time: Aim for a fast time (e.g., under 2 hours for the best ending) to unlock specific endings.
- Item Collection: Achieving 100% item collection (all Energy Tanks, Missile Tanks, Super Missile Tanks, and Power Bomb Tanks) is usually required for the absolute best ending, regardless of time.
- Image Gallery: Completing the game under various conditions (different times, item percentages, or difficulties) will unlock images in the game's gallery, providing concept art and character renders.
To see all the endings and unlock the entire gallery, you'll need to play through the game multiple times, experimenting with different playstyles and challenges. This adds significant replay value for completionists and fans of the Metroid lore.