Shoe & Karn are a pair of super-heavy tanks created by the Rebel Army for cooperative mission. They are each armed with one main turret-mounted cannon, two sub-cannon turrets on the front, and a missile launcher on the back. Two side-mounted hatches allow soldiers to help defend the tank as well, usually with bazookas or rocket launchers.
Beyond the color palette, the only difference between the two tanks is that Shoe's missiles fire off of a ramp. In Metal Slug Defense and Metal Slug Attack, Karn and Shoe's names are swapped, so Karn is the one with the ramp.
In Metal Slug SV-001, they appear as the game's fourth boss. They are each piloted by Sergeant Sagan Gail and Corporal Logan Gail (セーガン・ゲイル & ローガン・ゲイル). Their pilot uniforms also reflect their respective tank's painted highlights. Both tanks in this game have a ramp, so it is unclear which driver and tank is which.
The tanks are fought at the same time, Shoe on the top floor and Karn at the bottom. They drive from side to side. If the player is in front of a tank, it will fire its main cannons. If the player is behind it, a Rebel will fire a bazooka at the player from a hatch on the side. Regardless of the player's position, they will take turns raining missiles on them. Should either one of them is destroyed, the surviving tank will start firing its missiles faster than usual. Although they can run over a human enemy, they will not be able to move if the player blocks them with the SV-001.
A brown version of Karn appears as a miniboss in Mission 5, where it comes from behind the player while they're trapped by a gate. A similarly colored Shoe appears as a mini-boss in Metal Slug X, also in Mission 5.
Shoe & Karn Colors
|Karn: First of the Twins, can be encountered in the upper path, facing the opposite direction of the player.|
|Shoe: Second of the Twins, can be encountered in the lower part of the field, facing the player's direction.|
|Shoe & Karn (brown): A mini-boss version in Metal Slug and Metal Slug X. Shoe and Karn appear alone in their respective game's fifth mission.|
|Shoe MK II: A modified Shoe which is aptly named the "Wind God", appearing in Metal Slug Attack. It has a jungle camo-like finish.|
|Karn MK II: A modified Karn which is aptly named the "Thunder God", appearing in Metal Slug Attack. It has a violet finish.|
|Shoe (Amadeus): A Shoe that has been produced by the Amadeus Syndicate. It has a similar finish to its MK II counterpart and is piloted by the Valerian Bear AI Viola. Appears in Metal Slug Attack.|
|Karn (Amadeus): A Karn that has been produced by the Amadeus Syndicate. It has a much more brighter finish compared to its MK II counterpart and is piloted by the Valerian Bear AI Bubu. Appears in Metal Slug Attack.|
|Leone's Shoe: A Shoe that has been compromised by a tentacle Invader. Appears in Metal Slug Attack.|
- Shoe & Karn are based on the German VK 4501 (P) heavy tank prototype and Tiger II heavy tank.
- Karn also appears in Metal Slug Mobile 3, but is never seen during gameplay.
- An early concept of Shoe & Karn's model is depicted with a two-barreled anti-aircraft cannon instead of the cruise missiles found in the game's final version.
- Shoe & Karn's sub-turrets bear a resemblance to the British Medium Mark III medium tank, the Russian T-28 medium tank and the Japanese O-I super-heavy tank prototype.
- Shoe & Karn's artwork depicts the tanks as blue, while in the games themselves Shoe & Karn come in three colors: brown, gray and purple.