system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why have all major cell phone games fallen into the same categories and are basically the same game with a different coat of paint?

I noticed this recently. Whether it's Star Wars and the Marvel Champions fighter, or Clash of Clans and Dungeon Keeper and any number of other games, nobody seems to be doing any kind of innovative gameplay. There is such a big audience, why not develop all kinds of different games?

EDIT: And are there any developers who have bucked this trend?

EDIT: Thanks for all the great answers. I guess it was kind of what I figured, but there are a lot of nuances to the industry that I wasn't aware of. Cheers.
gpt
No protection for creators of mechanics in games. Candy Crush is Bejewled which was probably something before that, Angry Birds is Crush the Castle, etc. 

Lack of curation by Apple, Google , Amazon, they just let any shit on their service so long as they are taking a cut and can market "One million Apps Launched" 

Most players are not "gamers" most gamer culture knows these games are shit but its not the target audience. Your mom is, not kidding.