• OpenTTD: Open Source and available for free.
• Settlers 2 via some DosBOX version. Back when I still used Android I used Dosbox Turbo, but it seems to have been removed from the Play Store. No clue which DosBOX build for Anrdoid is good nowadays…
• 2048: Open Source and free puzzle game
• Threes: Puzzle game similar to 2048
• Cogs: Puzzle game. No clue how to find it on the play store, but it’s available at humblebundle.
• Slay the Spire: Deck Builder roguelike.
• Space Chem: Zachlike puzzle game. (Actually not only zachlike - it’s form zachtronics)

and basically any Android game that ever was part of a Humble Mobile Bundle. Those happened before Humble Bundle was sold and consequently became boring.