Multiplayer twin stick shooter games for PC/Windows with online support

ProtoGalaxy

Players: 4 local, 4 online

Narco Terror

Players: 2 local, 2 online

Dual Core

Players: 4 local, 4 online

SCALPERS: Turtle and the Moonshine Gang

Players: 4 local, 4 online

NoReload Heroes

Players: 4 local, 4 online

Gunnheim

Players: 4 local, 4 online

Wanted Corps

Players: 2 local, 2 online

Dead Sky

Players: 0 local, 4 online

Guardians of Orion

Players: 0 local, 4 online

Zombie Estate 2

Players: 4 local, 4 online

Congo

Players: 0 local, 4 online

Meltdown

Players: 0 local, 4 online

A Mass of Dead

Players: 0 local, 4 online

God's Trigger

Players: 2 local, 2 online

Trident's Wake

Players: 4 local, 4 online

The Mutational

Players: 0 local, 4 online

Livelock

Players: 0 local, 3 online

Monsters and Monocles

Players: 4 local, 4 online

Death Carnival

Players: 4 local, 4 online

Blacklist Brigade

Players: 0 local, 4 online

Dead Motherland: Zombie Co-op

Players: 0 local, 4 online

Stardrift Nomads

Players: 0 local, 8 online

Deathpit 3000

Players: 0 local, 2 online

Serious Sam's Bogus Detour

Players: 4 local, 12 online

Reflex Unit 2

Players: 0 local, 2 online