You can tweak things just a bit without getting unintelligible. Like Mad Max: Fury Road using chrome as an adjective. Firefly uses shiny a lot to mean good in general.
Well, that's not an accent, that's vocabulary, and plenty of shows do it, often to bypass censors. See Farscape's frell, frack. It's done in video games too - for example, 2077 has a pretty rich vocab
A creole is what happens when several groups with different native languages are put together and have to communicate. If you have people speaking the same native language in isolation you will eventually get a distinct dialect of the parent language, not a creole.
I thought that was pidgen so I looked it up if anyone is curious:
What is the difference between pidgin and creole? In a nutshell, pidgins are learned as a second language in order to facilitate communication, while creoles are spoken as first languages. Creoles have more extensive vocabularies than pidgin languages and more complex grammatical structures.
“A Clockwork Orange”, famously, was set in a post-Cold War setting where the West and Russia had grown close, and the who,s thing was written in a dialect that was part English and part Russian. But I agree with the other poster that in general it’s too much work.
In the novel I'm writing this occurs. Someone from 2004 is transported to a planet in the year 240,000. She learns the language, but she can't quite get the dialect down because humans have evolved different facial/vocal muscles by this point.
Obviously it's in writing so I can get away with not having to explicitly define the accent. 😅