Use every weapon in the game

Defeat 4 enemies with the same explosion (all explosive items and weapons apply)

Listen to all optional conversations in game

Beat the best score in the retro videogame

Find the Strange Relics

Defeat 5 armored enemies with melee only

Find all Journal Entries

Drive away in the jeep with Elena without killing any enemies

Repaired all Portals on Chaos Island.

Play in the ocean near the sunken ship

Just prior to City Chase, stand perfectly still for 30 seconds (stage demo fail)

Climb to the very top of the Clocktower in the City