Three that I like to play when commuting

Breakout 71 https://f-droid.org/en/packages/me.lecaro.breakout/ - This one is great though all the powerups make it a bit too easy if you play it for a while. But it's a good one if you just want get into playing something quickly.

Ball2Box https://f-droid.org/en/packages/com.simondalvai.ball2box/ - It's a pretty simple game but surprisingly addictive if you're like me trying to get a perfect score on each level (there's a ton of levels).

Calculate https://f-droid.org/en/packages/com.rechnen.app/ - Practice doing math in your head!