First the animation is like anime but the humans foreheads are big AF. So if you're trying to watch it, don't lose interest because the character designs.

I remember watching this in 06 on Cartoon Network.

The plot is simple. Teens find a super computer in a factory. The super computer has a world called Lyoko, a virus named X.A.N.A. And a girl named Aileta who was trapped in there. The plot is to stop X.A.N.A. and free Aileta. X.A.N.A would use a bunch of objects to try and kill either people or destroy the Factory. No Joke the first episode is it possesses a TEDDY BEAR. So it's automatically creative for obstacle wise against the Protags.

The Protagonists:

Jeremy: The Nerdy guy who is the leader.

Aileta: The trapped, rescued, amnesiac girl who gets her memories by the end and lives on earth.

Odd: The Joker of the group. He is always hungry and is sometimes the butt of the joke. But sometimes hes a sports guy and attempting 'Ladies Man'

Ulrich: He is the one that has Dad issues, you can tell he likes Yumi instantly but doesn't flat out say it every chance he gets, and is in love triangle.

Yumi: She is just a japanese girl that you can tell likes Ulrich but can't say it, and gets in a small love triangle.

The Side Characters are also a good also. They are fleshed out and you can sometimes sympathize with them.

The show is 4 seasons long. It is a 2D anime style when in the 'real world' and 3D Anime style in 'Lyoko'

So around season 1 they managed to actually Get Aileta out. But she has a virus. So they need to get that. Aileta has her own arc about her past since she can't remember anything. Her father was revealed to make Lyoko and was still there. Soon around season 2-3 we meet a new character named William.

William: The transfer student who is the to cool for school guy. He's there for the love triangle to exist.

He was part of the love triangle too. catches on with what the gang is doing and joined them... And on his first mission he Fails. And when I say fail, I mean he gets possessed, kills the people on Lyoko... and destroys it entirely. Yes... Lyoko got Destroyed.

So Instantly they Raise the Stakes with this. There were episodes before with the core being destroyed. But I thought oh, he would have been stopped. I was shocked. So now they had to Stop X.A.N.A, Free Aileta from the Virus, and Save Willam from being corrupted.

After 4 seasons, Ailetas Dads sacrefice, and a bunch of fighting. They managed to save everyone and shut the supercomputer off. And Thats the end. I would mention Code Lyoko Evolution... but it's just dog śhït.

So this show had crazy ways to raise the stakes, some people actually could die. The characters go through some arcs that change there characters completely. But Not Odd. He stays the same.

So this is honestly my Number 1 favorite show for cartoon wise.