Games like Monsters sandbox
Games like Monsters sandbox include Left 4 Dead 2, Killing Floor 2, Back 4 Blood, World War Z, and DayZ. We matched them by the tags players give Monsters sandbox on Steam (Arena Shooter, Hack and Slash, Zombies, Aliens, and Gore): closest matches first, and among equally close ones the better-known games.
Left 4 Dead 2
Shared: Zombies · Multiplayer · Co-op
Killing Floor 2
Shared: Zombies · Gore · Multiplayer
Back 4 Blood
Shared: Zombies · Multiplayer · Online Co-Op
World War Z
Shared: Zombies · Multiplayer · Online Co-Op
DayZ
Shared: Zombies · Multiplayer · Online Co-Op
Warhammer: Vermintide 2
Shared: Hack and Slash · Co-op · Multiplayer
HELLDIVERS™ 2
Shared: Online Co-Op · Multiplayer · PvE
MORDHAU
Shared: Multiplayer · Gore · Hack and Slash
Dying Light
Shared: Zombies · Online Co-Op · Gore
Call of Duty®: Black Ops III
Shared: Zombies · Multiplayer · Shooter
Serious Sam 3: BFE
Shared: Gore · Co-op · Multiplayer
Dead by Daylight
Shared: Multiplayer · Gore · Online Co-Op
Left 4 Dead
Shared: Zombies · Multiplayer · Co-op
Killing Floor
Shared: Zombies · Co-op · Multiplayer
Call of Duty®: Black Ops Cold War
Shared: Zombies · Multiplayer · Action
Call of Duty: World at War
Shared: Zombies · Multiplayer · Co-op
Starship Troopers: Extermination
Shared: Online Co-Op · Multiplayer · Aliens
Blood and Bacon
Shared: Gore · Multiplayer · Shooter
No More Room in Hell 2
Shared: Zombies · Multiplayer · Online Co-Op
Pavlov
Shared: Multiplayer · Zombies · Gore
Diablo® IV
Shared: Hack and Slash · Online Co-Op · Multiplayer
Call of Duty®
Shared: Multiplayer · Shooter · Action
Fistful of Frags
Shared: Arena Shooter · PvP · PvE
Call of Duty®: Black Ops
Shared: Zombies · Multiplayer · Action