Botkiller weapons are a special classification of items. They are signature Stock weapons for each class with either a robotic Heavy's or robotic Engineer's head with glowing, team-colored eyes bound to the weapon with various belts, chains, and wires, depending on the weapon. There are six types of Botkiller weapons: Silver, Gold, Rust, Blood, Carbonado, and Diamond. All of the Botkiller weapons are Jiggleboned; for all classes besides the Engineer and Spy, robot heads sway left and right according to the direction the player turns. On the Engineer's and Spy's weapons, the mouth of the robot head opens and closes while the player moves around. The Sniper's, Demoman's, and Medic's Botkiller weapons are also slightly different: the Sniper Rifle's robot head has a hole in its forehead, the Stickybomb Launcher's sports a metal eye-patch (except for the Silver and Gold Mk.II), and the Medi Gun's has its robotic brain exposed.
Botkiller weapons were added to the game with the Mann vs. Machine update on August 15, 2012 Patch. To earn a Botkiller weapon, the player must complete a full Tour of Duty, after which they are rewarded with a random Botkiller weapon. Typically, the obtained weapons are Rust (from Operation Oil Spill), Silver (from Operation Steel Trap and Operation Mecha Engine), or Carbonado (from Operation Gear Grinder); however, there is a small chance of the respective types instead being a Blood, Gold, or Diamond variation. Weapons with the robotic Engineer head can only be obtained in the Silver and Gold variations from Operation Mecha Engine.
Botkiller weapons are always in Strange quality. A Botkiller weapon's level matches the badge level for the current operation at the time it was issued, up to level 255, after which it to level 0. The first tour completed on an account always drops a level 1, so a minimum of 256 tours are required to create a level 0.
- The yellow components of the silver heads are set up for paint.
- There is an unused "Uranium" texture left in for the head that gives the rusted style a bright yellow-green glow from the seams.
- There is an unused "Mirror" texture left in the game files that gives the head an incredibly shiny appearance.
- Robot heads issues:
- Robot Heavy heads may fall off of their Botkiller weapons, predominantly the Botkiller Minigun, and attach to other weapons.
- Robot Heavy heads stay attached to the player's ragdoll upon death, no matter which weapon was currently held upon death.
- The loop attaching the robot head to the barrel of the Carbonado and Diamond Botkiller Medi Gun is not well-attached to the barrel and can swing partly or entirely through the barrel in the client view.
- With flipped viewmodels enabled, the Botkiller Wrench's robot head, of all types, has its normals inverted, making it appear to be see through.
- The Robot Heavy Head on the Diamond and Carbonado Botkiller Minigun appears to be twisted 90 degrees to the right in the client view.
- The Carbonado and Diamond robot heads do not Cloak on friendly cloaked Spies or in client view.
- Spies that disguise while holding a Botkiller Knife of any kind have the robot head disappear from their Knife in world view.
- Inspecting a Botkiller Knife results in a broken animation, causing the wires and the head to clip through itself.
- Inspecting a Botkiller weapon in the inventory screen only shows the Stock version of the weapon.
- Equipping a Botkiller weapon causes the class select animation to not play, with the exception of the Wrench and Knife.
- Weapon skin issues:
- In world view, the Carbonado Botkiller Stickybomb Launcher may appear as Scottish Resistance (though without the sensor camera).
- In world view, the Gold Botkiller Minigun may appear as Natascha (though without the ammo belt).
- In first person view, the Rust Botkiller Flamethrower has an unlit pilot light.
Botkiller Scattergun variant first person view.
Botkiller Rocket Launcher variant first person view.
Botkiller Flame Thrower variant first person view.
Botkiller Stickybomb Launcher first person view.
Silver Botkiller Minigun Mk.I variant first person view.
Silver Botkiller Minigun Mk.II RED variant first person view.
Silver Botkiller Minigun Mk.II BLU variant first person view.
Silver Botkiller Wrench Mk.I variant first person view.
Botkiller Medi Gun BLU variant first person view.
Silver Botkiller Sniper Rifle Mk.I variant first person view.
Silver Botkiller Sniper Rifle Mk.II RED variant first person view.
Silver Botkiller Sniper Rifle Mk.II BLU variant first person view.
Silver Botkiller Knife Mk.I RED variant first person view, ready to backstab.
Silver Botkiller Knife Mk.I BLU variant first person view.