Complex sentence: O'Neill's plays were among the first to include speeches in American vernacular and involve characters on the fringes of society, where they struggle to maintain their hopes and aspirations, but ultimately slide into disillusionment and despair.
Split into simpler sentences: O'Neill's plays were among the first to include speeches in American vernacular and involve characters on the fringes of society. They struggle to maintain their hopes and aspirations, but ultimately slide into disillusionment and despair.