There was these "game builders" on Nick.com from (i think) 2010 to (i think) 2014. You could select a character, and design a level to create. Once you created the level, you could upload it to Nick.com and people would be able to play the levels you made. There was one for SpongeBob, one for the Last Airbender movie, one for Fanboy and Chum Chum, one for iCarly, and one for The Penguins of Madagascar. There were even ones for Danimals, Honey Nut Cherrios, and Lucky Charms. I remember making games on the spongebob one.
Here is the splash screen for Spongebob game creator Here is the splash screen for the Last Airbender one Here is the splash screen for the Fanboy & ChumChum one Here is the splash screen for the iCarly one