Millions of apps have been uploaded to Apple App Store since the birth of it. Out of the huge number of apps, some hundreds of thousands apps have been removed from the store, leaving the total number of available apps to roughly 2.2 million (end of 2017). Apple has also taking active efforts to improve the quality of the cleaning the store from clone and spam applications.
It is still estimated that the number of apps will grow by another hundreds of thousands of new apps over the next years to come, which will mean the total number of apps and games is estimated to reach 5 million by 2020.
Some time ago somebody calculated that there were total 39,171 chances to get ranked in the App Store. That is how many spots on the top lists there were. This number has actually grown even bigger today, since Apple has added new feature spots to e.g. app and game category pages. So, we can say that there are a good number of feature spots available.
Despite these chances to get ranked, that are not that many apps in the App Store who are actually "alive". Meaning that only small portion of apps and games actually have an active user base and even smaller portion of them generate revenue for their developers. There is huge and constantly growing number of so called “Zombie apps”. And, we're not talking about Walking Dead and other similar kind of games here. These "Zombie apps" are considered “dead” because nobody can find them from the app store. These apps are practically invisible since they don’t rank in any of the App Store top lists, and they don't appear in the top search results either.
It's estimated that Zombie apps represent over 70% of the apps, which would mean the total number of them could be over 1.5 million. Historically, most of the Zombie apps have been in the Games category. Naturally, as it is the biggest category with most clones in it. But, also Books, Entertainment and Utilities have had relatively high percentage of zombie apps. The most hopeful category has been Kids which has the lowest number of zombies, only 9%.
Starting point in fighting against turning into zombie, is of course keeping up the development cycle and releasing regular updates of the app or game. Having a great quality and good supporting services in the eyes of the end users will help in getting good reviews and recommendations for organic growth. And organic growth, along with paid UA, will make the app or game get better ranking positions in the store charts.
The often forgotten tool for improving the ranking position in the App Store search is Keyword Research and Optimization. By paying attention to this area of the app's or games's presence in the store will most likely increase the chances of getting ranked higher in the search and found by the App Store users. Once the search visibility has been built, the app be boosted higher in the top lists with the help of App Marketing to gain a positive spin with organic downloads.