Knife an enemy without him ever knowing you were there in Single Player or Special Ops.

Kill 2 enemies with a single bullet in Single Player or Special Ops.

Defeat 20 enemies with the Pistole

Defeat three enemies with one explosion

Find ten treasures

Defeat 20 enemies with gunfire by aiming while hanging

Defeat 50 enemies with hand-to-hand combat

Defeat 20 enemies with headshots

Find one treasure

The player has restored the forests of Arcadia

The player has successfully invented at least one item

The player has acquired at least one weapon upgrade

The player has purchased one slot in any Plasmid or Tonic track