First App was a birthday calendar (Back in 2012-13), where I pulled Contact book, Google Plus and Facebook and at one time also had a section of born today. But it had bugs, it took too much time to solve. When I fixed things, Google Plus was shutting down, and FB APIs also got more restricted. I dropped working on that project.
Second App was a utility around a service called PushBullet: Still active and one of the must have utility back in the day, I developed an open-source utility around that app. I couldn't market it properly, (Didn't know real possibility of Product hunt or Hacker news back then). Then PushBullet went behind paywall and I stopped using it entirely. Also lost interest working on that project.
Third App was another utility managing (and intelligently deleting) files in Android Phones: Current Files App (Started as Files GO) didn't exist then. I worked on this longer than any other project. Even tried to do marketting, at it's peak (when I posted about the app on reddit) it had ~100 users a day, then daily job got on the way and I couldn't work on the app. Then Google Happened, their restrictive play store policy meant I have to chose between other aspect of life and this project. I dropped working on this....
Not counting many ideas that didn't go beyond failed or unconvincing POCs. I have stopped developing apps entirely since couple of years. Got some backend certificates, and now in a free time I indulge in Chess, Reading and writing blog post (80% in native language on non tech stuff and 20% on tech stuff).
Edit: Started working on a POC of a service I had in my mind since long. Let's see what happens.