Hi Michael! Thank you for your comment! It really depends on the context. The literal translation is “Tu vas bien”, which means “You are doing ok”. But if you are checking on someone or reassuring them, “Tout va bien” is a common expression in French.
"Je suis partant" does mean "I'm game" or "I'm in". The reason why it doesn't mean "I'm leaving" is because it is an idiomatic French expression so you cannot translate it literally.
If you want to say that you're leaving you'd rather say "je pars".