Monshou no Nazo has 2 parts - book 1 and 2. Book 1 tells the same story as Shadow Dragon, only the writing isn't nearly as good and neither is the gameplay. A few chapters were even removed. So I definitely wouldn't recommend it as an alternative. But book 2 is much better than book 1, so you could play it after Shadow Dragon. Or just wait for the book 2 remake to get fan-translated.
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My rivalry with SuperNiceDog turned out a bit one-sided.