RPG games seem to get overlooked for the standard fling-stuff, endless runner, and racing games, which is too bad, because I think RPGs are where you really get your money's worth for play value. These are the games I've been playing recently. All very fun, and easy to end up spending hours at a time on.
Tales of Illyria - $3.95 for the "early access" version. Great story (lot of reading), turn based battles, described as a mix of Oregon's Trail, choose your own adventure books, and D&D and I'd say that's accurate.
Knights of Pen & Paper - $1.99. Basically takes the experience of playing a sit-at-a-table pen and paper D&D type game and puts it into a phone game. Good replay value on this one too since you can choose different combinations of players and characters.
Bard's Tale - $2.99 (50% off price). This one's an action RPG. There's some IAP options to get items and talents faster and I personally was happy to buy them, it's still less than you'd pay for a console game, and imo more fun to play.
Yesterday -$2.49 (50% off price). Best way to describe it would be it's a detective-RPG where you have to figure out clues and has an interesting story. Pretty dark stuff though, not for small kids.
Puzzle Quest 2 - free for trial area, then $4.99 to unlock the full game with all characters. It's an RPG where the battles are done as puzzles to unlock attacks or spells.
Andor's Trail - free, no ads, no IAP. I got this back when I was on my OG Droid and still play it today. The game is in-progress so some quests can't be completed yet, and some areas don't exist yet, but it's got a good story, skills, choices to make that you can't go back on, and an update is expected maybe in a couple months.
And if you're a fan of card based games and 80s cartoons, you can register for this
G.I. Joe game from the makers of Blood Brothers to get a Stormshadow card.