Most are just free as opposed to free-to-play. I left out all the multiplayer games. They didn't seem like they attracted enough attention to have decent player pools.
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Ruby and The Lost Crystals on Steam
Ruby and the Lost Crystals is a calm third-person puzzle adventure where you swap between two characters to solve puzzles. Use physical interactions, magical projectiles, and object-swapping to unlock paths, reflect lasers, activate platforms, break obstacles, and explore ancient ruins.

Panzer Kliker mk I Yanks on Steam
Idle tank-building clicker game with retro pixel-art style. Assemble parts, recruit crew, and upgrade your war machine to climb the ranks - even while you're away!

Nirvana, Origin of Fate on Steam
3rd person procedural survival 3D Game. The game allows you to simulate the character's survival needs and find meaning in adventure, and create a bond with the other characters in the game, to develop their ability to control the elements of the island.

Hook, Line, and Axe on Steam
Swing into action in this third-person hack-and-slash parkour set in a sci-fi dystopian America. Strike down corruption with your trusty battle axe. Grapple onto enemies and the environment alike. Chain abilities for the ultimate combo of destruction in Hook, Line, and Axe.

Hog Heist on Steam
Don't get caught as you explore large museum exhibits, steal valuable items, evade law enforcement, and race back to your getaway truck in this exciting arcade game.

Lots of Cats on an Adventure on Steam
“Lots of Cats on an Adventure” is a game where you find hidden cats in comic strips, meow!

Curyeux on Steam
Dive into the mind of Lucienne, a tormented painter. Leap through emotional memories, solve puzzles where shapes deceive and emotion leads the way. A dreamlike platformer where each painting brings you one step closer to yourself.

Horizon Valley on Steam
Horizon Valley is an exciting endless runner where you'll encounter different types of scenarios. Your goal is not only to set a new record with every attempt but also to unlock incredible characters and ships that suit your style. You can obtain them through random chests, special spins, and more!

LostMagic on Steam
A 2D MMORPG with turn-based combat, dungeons, PvP, PvE in a unique world with story driven content.

Lo-Fi Golf on Steam
Chill out with a third-person, physics-based golf game set to relaxing LoFi music. Explore dreamy, atmospheric maps with the freedom to find your own path. Will you risk a tricky shortcut or play it safe? Every shot counts, complete each course before running out of strokes!

PyramidValley: Reborn on Steam
Immerse yourself in ancient Egypt with PyramidValley, a management game where you develop your pharaonic city by constructing iconic monuments and gathering various resources to ensure prosperity.

Doorway 2 on Steam
A fast-paced parkour game where you leap, slide, and crawl through intense obstacle courses—solo or online. Beat the clock. Dodge the bosses. Respawn, retry, and keep moving.