Flash had a really vibrant games ecosystem. And for a while it seemed like mobile would take up the torch for minigames, but it has really dropped it. It seems next to impossible to self publish, and the cross compilation frameworks never quite got to parity with native. I have seen some Indie PC games publish mobile versions, but they are never as good. And mostly they seem to exist because otherwise someone will straight copy your game and publish it to the app store, assets and all.
But this is indicative of the games industry. It is massive, but you look at the breakdown and most of its gambling with extra steps. So has the games industry grown, or the gambling industry using new media?
Like with hit movies, it's incredibly hard to predict just what's going to attract people's attention. At least Monument Valley was cheap to build, which is one of its biggest wins.