No-Bullshit Games keeps track of games available on iOS and Android that don't hit the player with ads, in-app purchases or other sleazy upsells. On both platforms we have The Room series, Layton: Curious Village, Stardew Valley, and the hot recent release Shattered Pixel Dungeon–and many more.
Report the bullshit
If one of the listed games is bullshit, please report it.
I thereby learned about the mobile edition of Mini Metro, bought at once. The site is maintained by Stavros, who writes that the single biggest problem the service faces is people submitting obvious bullshit with excuses for why the bullshit should be acceptable: "I apparently have failed to be explicit enough on 'no bullshit.'"