Inside the Code was a multiplayer map added in the 6.1.5 update.
Aiming is very hard on this map (unless using the Stinger or Smart Bullet Bazooka, due to its homing ability), as touching the floor bounces you upwards like the trampolines in the map Science Lab. There are many floating platforms scattered around you can stand on. Each team has three bigger platforms to spawn on, located at both the ends of the map. Each team spawns on one end.
Like "The Matrix", it is green and full of numbers 1 and 0, which resembles binary codes. It has blocks that you can stand on. The blocks are black with neon green outlines. Also, the map is anti-gravity, making it difficult to land on the platforms. The color scheme in this map is neon green, and causes your skin and weapon a green shade.