There is a shop simulation game on Android. Fun little game, you run your little shop and grow it, the graphic is pleasant and music too, the game really sucks you in.
There is also this one feature, you have the ability to watch ads and gain certain bonus like 2x more customers, 2x faster cashiers yadda yadda. It seems cool and helpful...
...however, after progressing more and getting attached to the game, you quickly realize that you've stopped progressing, everything is so slow and expensive so naturally you use the ad boosters.
In the end you willingly watch 3x ads every two minutes so your shop progresses, but even then that's not enough and you'll be forced to pay for premium currency to progress.
So in the end you're left with ad simulator where you willingly watch ads 75% of your playtime. The guy who made the game is a genius, greedy one, but still.
And no, I didn't spent a cent on that game. I've left it the moment I've realized the pattern.