I am writing my Sherlock Holmes game right now. It's based on the original book, and so far, I've done the first three stories, which is about 30,000 words total. For the fourth story, I don't know if I want to do "The Boscombe Valley Mystery" or "The Man with the Twisted Lip". Any preferences? They're both fine stories, but "The Man with the Twisted Lip" is more popular.
The book has 12 cases, but I was thinking of only doing four. That way, if my game is popular, I can make a Volume 2 and a Volume 3. Alternately, I could do all 12 cases and use the second Sherlock Holmes book for sequel material, but that's tripling my workload.
Another option is to do four mysteries, and have The Valley of Fear as a finale case. That's a Sherlock Holmes mystery book, which is about three times longer than the average story. Seems like a good length for a finale case, right?