While itch.io generally lets creators do whatever they want in terms of sales there seems to be a huge number of games for Android, Linux, Mac, and Windows that are all free until 13th July:

• Dusk Slayer, roguelike
• Eldoria, survival RPG
• Caesura - Sparkles of Lie , mystery RPG
• It's Frogzen, puzzle
• Color Mind, puzzle
• Poly Snakes, arcade
• Exo Track, hacking sim
• You Could've Gone, platformer
• FlyTrap, scavenger hunt
• Binky Saves the World, co-op puzzle
• Ale and Tattles, restaurant manager
• Scavenge, spooky collectathon
• Balloon Fest, arcade
• Tiny Tails: The Whale’s Tale Story, mystery
• Ghosto, endless runner
• Bill Essenol and Lohafta's Light, platformers
• E'gduj, spooky adventure
• Shadow of Lir'Ah, Iron Crops, and User N, platformers
• Kingdom Clicker, apparently just a clicker