In mission 1 obtain H11 in hidden cave to unlock Colorado Rockies MP Arena
Acquire every weapon available in mission 1
Complete mission 1: Colorado Mountains
Complete mission 1: Colorado Mountains on Hard difficulty
Complete mission 2: McKenzie Airbase Interior
Complete mission 2: McKenzie Airbase Interior on Hard difficulty
Complete mission 2 in less than three minutes to unlock Goofies MP Characters
In mission 3 obtain binoculars to unlock Caves MP Arena
Complete mission 3: Colorado Interstate 70
Complete mission 3: Colorado Interstate 70 on Hard difficulty
Acquire every weapon available in mission 3
Complete mission 4: I-70 Mountain Bridge
Complete mission 4: I-70 Mountain Bridge on Hard difficulty
Complete mission 5: McKenzie Airbase Exterior
Complete mission 5: McKenzie Airbase Exterior on Hard difficulty
Complete mission 6: Colorado Train Ride
Complete mission 6: Colorado Train Ride on Hard difficulty
Complete mission 7: Colorado Train Race
Complete mission 7: Colorado Train Race on Hard difficulty
Complete mission 8: C-130 Wreck Site
Complete mission 8: C-130 Wreck Site on Hard difficulty
Complete mission 8 in less than three minutes to unlock Syphon Filter 1 MP Characters
In mission 8 kill Steven Archer with headshot while he attempts to escape to unlock Park Jungle Gym MP Arena
In mission 9 obtain girly mag to unlock Pharcom Incubator Lab MP Arena
Acquire every weapon available in mission 9
Complete mission 9: Pharcom Expo Center
Complete mission 9: Pharcom Expo Center on Hard difficulty
Complete mission 10: Morgan
Complete mission 10: Morgan on Hard difficulty
In mission 11 kill three guards before they shoot down disco ball and throw grenades to unlock Disco Basement MP Arena
Complete mission 11: Moscow Club 32
Complete mission 11: Moscow Club 32 on Hard difficulty
Acquire every weapon available in mission 11
In mission 12 obtain PK-102 from one of the crashed cars to unlock Rhoemer's Bunker MP Arena
Acquire every weapon available in mission 12
Complete mission 12: Moscow Streets
Complete mission 12: Moscow Streets on Hard difficulty
In mission 13 kill guard before he blows up car and obtain BIZ-2 from it to unlock Surreal MP Arena
Complete mission 13: Volkov Park
Complete mission 13: Volkov Park on Hard difficulty
Complete mission 14: Gregorov
Complete mission 14: Gregorov on Hard difficulty
Complete mission 15: Aljir Prison Break-In
Complete mission 15: Aljir Prison Break-In on Hard difficulty
Complete mission 15 without using the crossbow to unlock Aljir Prison MP Arena
Acquire every weapon available in mission 16
Complete mission 16: Aljir Prison Escape
Complete mission 16: Aljir Prison Escape on Hard difficulty
Acquire every weapon available in mission 17
Complete mission 17: Agency Bio-Lab
Complete mission 17: Agency Bio-Lab on Hard difficulty
In mission 18 obtain M-79 in operating theatre to unlock Agency Computer Lab MP Arena
Complete mission 18: Agency Bio-Lab Escape
Complete mission 18: Agency Bio-Lab Escape on Hard difficulty
In mission 19 obtain dirty laundry from washing machine to unlock DC City Park MP Arena
Complete mission 19: New York Slums
Complete mission 19: New York Slums on Hard difficulty
In mission 20 obtain M-79 on top of the car park stairs to unlock Syphon Filter 2 MP Characters
Acquire every weapon available in mission 20
Complete mission 20: New York Sewer
Complete mission 20: New York Sewer on Hard difficulty
Complete mission 21: Finale
Complete mission 21: Finale on Hard difficulty