Currently Online 
Google Play Pass includes some good mobile games and ported classics, but most of these games are quite old and have been on sale many times: https://www.androidauthority.com/google-play-pass-games-apps-1032500/
So if you are into mobile gaming, you probably already have a lot of these games (which is of course a similar issue for most other game subscriptions on PC and consoles).
On the other hand, Apple Arcade has a lot of brand new games. I'm currently playing these new games on my iPad Pro:
- Oceanhorn 2 (would probably cost around $9 / €9 like its predecessor, which I liked very much)
- Jenny LeClue (costs almost $20 on Steam, almost backed the Kickstarter for $15 a few years ago)
- Tangled Tower (probably around $10 on Steam, GOG and Switch, when it is getting released there at October 10th)
- Shantae and the Seven Sirens: Part 1 (awesome preview to the new unreleased Shantae game)
- Sonic Racing (looks great, plays okay, I can't rate balancing so far)
- Grindstone (I love the humor and animations of this casual puzzle/strategy game)
