>>1550840All free, with minimal/no ads.
BuriedBornes. Simple, no-nonsense rogue-lite that's a great time-killer.
Void Pyramid. Odd little RPGMaker game that you can easily pick up. Simple, but with a lot more thought put into it than you might initially give it credit. I think a fair few RPGMaker games can also be played on phones, so if any catch your eye they're worth a shot.
A good DS/GBA Emulator. A lot of old titles play very well on a phone, and you'll get stuff that works perfectly fine offline and is a lot better than your average cash-grab app.
