I'm looking for a license to put on some projects that REQUIRES modification in order to redistribute. Any help in the search, insights, or feedback, is very welcome.
So you are concerned about copyright? I'd look into the creative commons license which states people can freely download your work, but must modify the items in a creative and original way in order to redistribute. More here: https://creativecommons.org/licenses/ I think it doesn't covers the redistribute entirely, I think its an option though.
I don't think I personally can go into detail, but most gpl (general public licenses) give the option to modify how it works, I think you can get a license which terms states people are not allowed to distribute copies. There isn't too much I can say about this (im no lawyer).
You can simply write your own license. Though I never heard of one that specifically states you must modify to distribute.
Yeah, that's basically it, Apple does it, pretty much any company or artist/coder can do it as well. Though when you do it, you'll want it to be legally applicable.
Start with a standard license that requires permission for use and distribution. Add a clause at the end that permission is automatically granted for derivative(modified) works. /not_a_lawyer