Top-rated old games that don't have sequels/prequels (yet)

Making sequels is like mining for gold. You could strike it lucky and find rich veins of sparkly gaming gems, or you could bust a sewer pipe and get covered in turd. For every Uncharted 2 theres a Duke Nukem Forever, and for every Resident Evil 4 theres a Resident Evil 6. But what about those games that never produced any follow ups?

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