I’d suggest looking through F-Droid, IzzyOnDroid and other FOSS repos for mobile games. I’ve found a bunch of mobile games that have as much depth as the ad-laden ones.

Hell, the reason I got back into mobile gaming recently was because the developer of Poinpy decided to make their game free on Google Play, remove microtransactions, and make the entire game playable from start to finish with extra modes. It feels like a Nintendo game in the best possible way. The main character Poinpy even looks like Kirby, which is reinforced by the ending of the game.

It’s ironic that even Nintendo hasn’t gotten mobile gaming down pat, either going the gacha route with Mario Kart Tour and Fire Emblem: Waifus, or trying to do the paid model and failing at it with Mario Run and Animal Crossing: Pocket Camp.