The game's ending depends on the choices you make throughout the story. You can achieve one of several endings, including:
BioShock 2 is a more action-focused but emotionally deeper game than the original. By following this walkthrough—sparing all characters, adopting all Little Sisters, fully researching enemies, and using Plasmids like Insect Swarm and Hypnotize—you will achieve the best ending and unlock the full narrative payoff: walkthrough for bioshock 2