Thousands of ways to communicate exist throughout history and fiction.
Creating a small number of setting-specific languages adds depth and interest to the setting and creates more opportunity for roleplay and story.
☐ NAME
What do the speakers of this language call it?
☐ FORM
What forms can this language take: spoken, written, or gestured?
☐ PLOT HOOKS
What secrets does this language conceal?
Fantasy: Dwarvish :: Elvish :: Orcish :: Goblin :: Draconic :: Thieves Cant
Modern: By Ancestry or Nationality
Futuristic: By Ancestry, Nationality, or Species