Multiplayer action/adventure games for PC/Windows with 4-player online support

Conan Chop Chop

Players: 4 local, 4 online

Void Crew

Players: 0 local, 4 online

Cave Crawlers

Players: 0 local, 10 online

Risk of Rain

Players: 4 local, 4 online

Sea of Thieves

Players: 0 local, 4 online

Son of Nor

Players: 2 local, 4 online

Don't Starve Together

Players: 0 local, 6 online

Terraria

Players: 0 local, 8 online

Super Dungeon Bros

Players: 4 local, 4 online

Windward

Players: 0 local, 4 online

Portal Knights

Players: 2 local, 4 online

The Wild Eight

Players: 0 local, 8 online

No Man's Sky

Players: 0 local, 32 online

Half Dead 3

Players: 2 local, 4 online

Necropolis

Players: 0 local, 4 online

The Binding of Isaac: Rebirth

Players: 2 local, 4 online

How to Survive 2

Players: 4 local, 4 online

A Valley Without Wind 2

Players: 0 local, 8 online

A Valley Without Wind

Players: 0 local, 16 online

CastleMiner Z

Players: 0 local, 8 online

ToeJam and Earl: Back In The Groove

Players: 4 local, 4 online

Watch Dogs: Legion

Players: 0 local, 4 online

Assassin's Creed IV: Black Flag

Players: 0 local, 4 online

Watch_Dogs 2

Players: 0 local, 4 online

Disney Infinity 2.0: Marvel Super Heroes

Players: 2 local, 4 online