its just not possible to correctly filter all ingame chat if the context of the content being filtered is constantly changing (that is natural language).

you could regex out the obvious profanities, but at the end of the day i feel theres not much point, you probably wont get very far asking your users to kindly not swear either :( such is life

I don't think you can filter everything, but you could match against a wordlist discarding non_characters. You could also convert much used replacement characters to their respective char counterpart. @ -> a, 4 -> a, $ -> s etc and check those as well...

Greetings.