This app was mentioned in 27 comments, with an average of 1.44 upvotes
I've been playing Unison League and enjoying it. The quests are short battles in a team of 5, either CPUs or with other online players, that take about a minute or two. You just press buttons to fire off each "skill".
At the end you collect loot drops and use them to level up your best weapons/armor and you can customize your appearance separate from what items you actually have equipped for combat. I usually spend a few minutes at a time through the day or do a chunk of like fifteen minutes.
It's totally free to play, without ads. There's a shop, but rarely for this type of game, I've never once felt like I was being pressured to buy anything.
I also like Hunt Cook. Super cute little game where you hunt and run a restaurant. You only get three "hunts" at a time and they take a while to recharge so you definitely won't be spending hours on it. Do your hunts, collect your vegetables, and throw some stuff on the stove.
Have you tried Unison League? https://play.google.com/store/apps/details?id=en.co.atm.unison&hl=en
you will thank me