Multiplayer first person shooter games with 4-player online support

Serious Sam HD: The First Encounter

Players: 4 local, 360 online

Call of Duty: Black Ops 3

Players: 4 local, 0 online

Synergy (HL2 mod)

Players: 16 local, 0 online

Starship Troopers

Players: 8 local, 0 online

Team Fortress 2

Players: 6 local, 0 online

Aliens vs Predator

Players: 4 local, 360 online

Tom Clancy's Rainbow Six Vegas

Players: 4 local, 0 online

Call of Duty: World at War

Players: 4 local, 0 online

DOOM 3: Last Man Standing (Mod)

Players: 16 local, 0 online

Call of Duty: Black Ops 3

Players: 4 local, 0 online

Duke Nukem 3D

Players: 8 local, 360 online

Mission Against Terror

Players: 8 local, 0 online

AirBuccaneers

Players: 16 local, 0 online

Interstellar Marines

Players: 4 local, 0 online

Space Hulk: Deathwing

Players: 4 local, 0 online

Sniper Elite 4

Players: 4 local, 0 online

Duke Nukem 3D: 20th Anniversary Edition World Tour

Players: 8 local, 0 online

Fallout 76

Players: 4 local, 0 online

Hexen 2

Players: 8 local, 0 online

Aliens vs Predator (1999)

Players: 4 local, 0 online

Vietcong

Players: 4 local, 0 online

God Mode

Players: 4 local, 0 online

Brink

Players: 8 local, 360 online

Aliens vs Predator

Players: 4 local, 0 online

Operation Flashpoint 2: Dragon Rising

Players: 4 local, 360 online