Multiplayer first person shooter games with 2-player online support

Serious Sam HD: The First Encounter

Players: 16 local, 0 online

Star Trek Elite Force 2 (HZM Co-op Script Mod)

Players: 12 local, 0 online

DOOM II

Players: 4 local, 360 online

Battlefield: Bad Company 2

Players: 4 local, 0 online

The Darkness II

Players: 4 local, 0 online

Call of Duty: Black Ops

Players: 6 local, 0 online

Aliens vs Predator

Players: 4 local, 0 online

Painkiller Resurrection

Players: 4 local, 0 online

Serious Sam HD: The Second Encounter

Players: 16 local, 0 online

Conflict: Vietnam

Players: 4 local, 0 online

Delta Force: Black Hawk Down

Players: 4 local, 0 online

Marathon: Durandal

Players: 8 local, 360 online

Call of Duty: Black Ops Cold War

Players: 4 local, 0 online

Battlefield 3

Players: 2 local, 360 online

ORION: Prelude

Players: 5 local, 0 online

Syndicate

Players: 4 local, 0 online

Wolfenstein: Youngblood

Players: 2 local, 0 online

Battlefield: Bad Company 2

Players: 4 local, 360 online

Aliens: Colonial Marines

Players: 4 local, 0 online

Turok

Players: 4 local, 360 online

Brink

Players: 8 local, 0 online

Generation Zero

Players: 4 local, 0 online

Conflict: Denied Ops

Players: 2 local, 0 online

Battlefield 3

Players: 2 local, 0 online

PAYDAY: The Heist

Players: 4 local, 0 online