Hey there. I'll tell you where you can take inspiration. Many who wanted to make the game wondered: "Where can I get inspiration from?". Indeed, where is it from? You can get inspiration in many ways.
1. Reading books. Yes reading books. After reading the book, you can gain a lot of inspiration. Look for a series of games "The Witcher". The game is made based on the books by Andrzej Sapkowski.
2. Games. They also can find a lot of inspiration. Just do not plagiarism game.
3. Films. You can try to do the same atmosphere. from movies, thrillers can get a good horror. Well, it's probably all. Good luck to everyone.
4. Drugs. By this you can create a lot of interesting games.Better not to use this method (This does not concern you if you are from Colombia or from Jamaica)) )
5.History. As mentioned JerkTheRipper can make a game based on the story. The exact same game "Valiant Hearts: The Great War" - made on the basis of historical data.
6.Psychology. You can make a game using human psychology. You can make a game that will soothe you, and you can make the game so that you'll want to throw your computer out the window).