I'd like to clarify a little: Things like TF2, No More Heroes or similar games arent cartoony games. Just cause they are rendered in a cartoon-style.
A cartoony game is for example like Sly Cooper series; A bunch of animals using odd gadgets, fun humor and cunning to pull of jobs to steal, well, god knows what off master criminals, who also are animals. It's humor, and premise is cartoony.
Or Jak & Daxter, a...thing..And a weasel standing up against..other..things. Whatever all the things in those games are..Anyway.
For example. A war game like tf2 is not a cartoony game, it has blood, violence and god knows what.
A cartoony game is games like Crash Bandicoot, Sly Cooper, Radget & Clank. It's story is cartoony, characters cartoony, world cartoony. And the game itself is cartoony.
And a "cartoony" game dont actually have to look like a cartoon. GTA 4 could've easily been a cartoony game, had its world, characters and story been different.