One in the Chamber

One in the Chamber is a non-team-based, competitive game mode for Zombies created by RisingSun2013 for 2-4 players, although it can also be played in solo as a co-op-style mode. It is based off the game mode of the same name from multiplayer.

Summary
Players only start with either a Ray Gun or the starting weapon of the map (for maps which don't have the Ray Gun), as well as their melee weapon, and only have one bullet in the magazine with no reserve ammo. More ammo is gotten by killing zombies and picking up the Max Ammo power-ups they drop. However, only one bullet is given per power-up, ammo is only given to the player who picked it up, and the player's weapon can only hold up to one normal magazine of the weapon's worth of bullets at once. Zombies have much lower health and the weapon the player gets is always a one-shot kill, even through splash damage. The melee weapon the player gets is also a one-hit kill up to round 10, when it becomes - and stays - a two-hit kill for the rest of the match. Players are also given extra health in maps where zombies can kill the player in two hits, allowing the player to survive up to three hits. Players cannot buy anything in the map except for doors, although opening them is free (except in solo, where they cost their normal amounts). Power-ups other than Max Ammo and Random Perk Bottles are not available in this mode.

As mentioned above, players can collect Random Perk Bottles, which gives the player who collected it a random Perk-a-Cola available on the map. They are given randomly from killing zombies. They cannot give the player a perk which cannot take effect in this mode (for example, Mule Kick since the player only gets one weapon for the whole match).

Players must compete to be the last alive, just like Grief and Cage Match. Also like said modes, the player must survive the round they are on in order to win.

Trivia/Notes

 * No noise is made when collecting a Max Ammo power-up, since they would cause too much noise collecting so many.