Multiplayer shoot em up games for PC/Windows with 2-player online support

Mercenary Kings

Players: 4 local, 4 online

Chicken Invaders: Ultimate Omelette

Players: 0 local, 4 online

Shoot Many Robots

Players: 0 local, 4 online

XenoRaptor

Players: 4 local, 8 online

Revolution Ace

Players: 2 local, 2 online

Rogue Continuum

Players: 4 local, 4 online

Cyborg Rage

Players: 0 local, 2 online

Shock Troopers

Players: 2 local, 2 online

Toon Shooters 2: The Freelancers

Players: 0 local, 5 online

Zombie Party

Players: 4 local, 4 online

RiftStar Raiders

Players: 0 local, 4 online

Rogue Robots

Players: 4 local, 4 online

GundeadliGne

Players: 2 local, 2 online

BlastZone 2

Players: 2 local, 2 online

WAVECADE

Players: 0 local, 2 online

sunny-place-2

Players: 0 local, 8 online

Chicken Invaders: Revenge of the Yolk

Players: 2 local, 4 online

Chicken Invaders: Cluck of the Dark Side

Players: 2 local, 4 online

Chicken Invaders Universe

Players: 0 local, 99 online

Astrosmash

Players: 4 local, 4 online