This is partly Apple faults. They only allow you 100 letters for keywords, they no longer index the description, and they provide no feedback on what users used

This is partly Apple faults. They only allow you 100 letters for keywords, they no longer index the description, and they provide no feedback on what users used to find your app. So they give you no information that you could use to limit your searches. There are a number of workaround for this, and one is to upload the same game with slightly different title until you hit on the magic combination that gets you sales. It sucks to have worked hard on a game, and it fails because of the wrong combination of title and keywords.