Shattered Pixel Dungeon is great, it’s an open-source dungeon crawler. Neither adds, nor transactions, micro or otherwise. If you want to pay tho, there’s a donation link for the dev team.
And if you still want too play GBA games, check check out the Lemuroid emulator, it’s also open source and has no adds. Works for nintendoDS too.
You can find both of these on F-Droid. They’re also be on Google Play, but since I’ve only tried the F-Droid version idk if the other has adds.
Some stuff like that’s definitely happened to me. My dumbest defeat was after drinking a potion of levitation to get past some disintegration traps, accidentally tapped he wrong part of the screen, thought I might still have enough fuel to make it to the chest and I’d use my spirit chain on the way back… But nope, I fell right on a trap and died. I had an ankh, but not a blessed one, so even tho I could make it back to that room’s entrance I had no way to recover my bag.