Season 1: Ep. 3 - NanoZIM

Jhonen Vasquez & Rob Hummel April 13, 2001 (2001-04-13) Dib sneaks into Zim's base, takes incriminating pictures of Zim without his disguise on, and puts them on a floppy disk. Zim discovers Dib and shrinks to microscopic size to enter Dib's body via microscopic submarine. Zim accesses Dib's nervous system, giving him control of Dib's arms, and, as a result, making him crush the floppy disk. When Dib reveals he has a copy of the disk hidden in his house, Zim travels to Dib's brain to delete the memory of where the disk copy is hidden, and, as an added bonus, damage Dib's brain to the point where he will never be a threat again. Dib then swallows a mini-submarine (a creation of his dad's) and begins to fight Zim, using controls that look uncannily like a video game. However, due to Zim being inside of him, Dib begins to lose control, and Gaz, who thinks this is merely an online game, takes her brother's place and begins to play what she thinks is a video game. In the end, she manages to defeat Zim, thus saving Dib's life. This episode also features more intense computer generated sequences. Computer-generated imagery had been used in the series already, but this episode was the most demanding so far.[5]