Call of Duty: Black Ops 3 is very popular for its multiplayer modes where people from all over the world play online in gun battles. The game features an excellent single player mode too and some hidden modes.

There is one hidden game mode and one extra feature that can be unlocked while playing Black Ops 3. Gotta Be Mobile reports an arcade mode is hidden in the game, and a YouTube user found a way to unlock killer mannequins.

The arcade mode of Black Ops 3 is called "Dead Ops Arcade 2." To unlock this game mode, players will need to beat the first two single player missions. After beating these two missions, they will given access to the safe house.

Once in the safe house, players will access the data vault (the computer). They will scroll up to the left corner and press the hidden button. From here the Dead Ops Arcade 2 screen pops up and players can start playing the game.

Dead Ops 2 is an arcade style zombies game shown from the top down. Players will attack zombies with simple guns and flame throwers. Watch the video to see how to unlock the mode and the game in action.

A YouTube user found a way to unlock some killer mannequins in single player mode. Players will need to go to the map Nuk3town in order to unlock these mannequins which the YouTube user is calling "weeping angels."

In Nuk3town, players will go around the map shooting off both arms of all mannequins. There are many mannequins scattered around the map, some inside the buildings and some outside in the yards. Once all of the mannequins have their arms shot off, random mannequins will start attacking the player. Every time the player turns around, a stationary mannequin will get closer to him and try to hit him. These mannequins are not moving when they are looked at, but turn around and they attack the player.

Watch the video below to see these killer mannequins.