I've wasted too many hours on Shatter Pixel Dungeon.

You can get the source for OG Pixel Dungeon off GitHub, but there's a maintened version on the F-Droid store (Shatter Pixel Dungeon). There's some other free versions floating around too, not sure if they're on the F-Droid store too, but I know they're on the play store.

Super Tux Kart and MineTest. Both are on fdroid and have amazing modding capabilities . I will say modding them is part of the fun too.

• Forkys

• Lexica

• 2048

• Sudoku

• Minesweeper

• Anuto TD: very underrated

• Pixel Wheels

• Andors trail: only played a bit but hear its good

I can't say I've tried a ton but in searching for the same thing, I found Mindustry. It scratched this weird StarCraft-esque tower defense game that I didn't know needed scratched.

Mindustry https://anuke.itch.io/mindustry

There's an android fork of Endless Sky:
Main game - https://endless-sky.github.io/
Android github - https://github.com/thewierdnut/endless-mobile
Android repo - https://f-droid.org/packages/com.github.thewierdnut.endless_mobile/

Flowit (Fill all boxes with the color of their border) https://f-droid.org/packages/com.bytehamster.flowitgame/

2048 Open Fun Game (2048 game with AI, Replay, History and other fun features, Open Source, no ads) https://f-droid.org/packages/org.andstatus.game2048/

Minesweeper - Antimine (A puzzle game where you search for all hidden mines. ) https://f-droid.org/packages/dev.lucanlm.antimine/

Shattered Pixel Dungeon (A roguelike game based on Pixel Dungeon) https://f-droid.org/packages/com.shatteredpixel.shatteredpixeldungeon/

Blockinger (Tetris clone) https://f-droid.org/packages/org.blockinger.game/

Vector Pinball is solid for sure.

Get Lemuroid!!

Unciv, Rabbit Escape

Egyptian Mouse Pounce is a pretty fun card game.