Ratmaster I started 4 years ago with C2 and simple mobile games. From 8 games published to Android, only 2 got serious downloads. From all, the 2 games had 99% from all downloads. To be honest , I don't know why other games didn't get any success, but as the time get by, the downloads started to slow down. When I started I made $3-4/day from ads, but now it only brings me $0.3-0.5/day. Google Play is bad at promoting new games and the big money makers will always make money because they can invest in promotion. The Android market is over-saturated with crap games. I am also a solo developer and I don't ave the energy to also promote and develop my games.
When every new kid on the block can publish a game after spending 1 hour developing is normal that the market will be over saturated with crap loads of bullshit. The gold rush for mobile game industry is over in my opinion.