Just for giggles I collected some links here to some of the less known projects and engines (outside Unity, UE and Godot)

The market is well saturated indeed!

https://www.adventuregamestudio.co.uk/

https://twinery.org/

https://scratch.mit.edu/

https://editor.construct.net/

https://microstudio.dev/

https://gamemaker.io/en

https://www.buildgamebox.com/

https://gdevelop.io/

https://www.modd.io/

https://editor.p5js.org/

https://www.alice.org/

https://defold.com/

https://phaser.io/