Grand Theft Auto Iv -

Niko does not automatically regenerate health. To heal, visit hot dog vendors, fast-food joints, or restaurants. Armor is essential for survival as it effectively doubles the damage you can take from firearms.

Complete 30 "Most Wanted" missions and 20 "Vigilante" missions found in police vehicle computers. Quick References & Resources GTA 4 Guide - IGN grand theft auto IV

Complete all main missions and specific side tasks like Little Jacob’s drug deliveries and Brucie’s exotic exports. Niko does not automatically regenerate health

To achieve "Key to the City" (100% completion), you must finish more than just the main story: Complete 30 "Most Wanted" missions and 20 "Vigilante"

Win at least one game of pool, darts, and bowling, and beat the high score in the QUB3D arcade game.

It is recommended to play the original game first before diving into the DLCs ( The Lost and Damned and The Ballad of Gay Tony ) to avoid plot spoilers.