Looks like someone copied your game graphics

https://www.coolmathgames.com/0-number-twins

The graphics are copied from http://www.novelgames.com/en/numbertwins/

Another game with copied graphics: https://www.coolmathgames.com/0-maze

Original: http://www.novelgames.com/en/maze/

The game itself isn't copied, as the fake game is Flash and the original is HTML5.

This game is straight-up copied from Novel Games: https://www.coolmathgames.com/0-math-man

Original: http://www.novelgames.com/en/mathman/

The only differences I could find are that leaderboard and references to Novel Games are removed. I tested them in my tablet and both the copy and the original are HTML5 and add the arrow controls.

Another game with copied graphics: https://www.coolmathgames.com/0-mazerace2

Original: http://www.novelgames.com/en/mazerace2/

Another game with copied graphics: https://www.coolmathgames.com/0-kakuro

Original: http://www.novelgames.com/en/kakuro/

Another game with copied graphics: https://www.coolmathgames.com/0-mousetrap

Original: http://www.novelgames.com/en/mousetrap/

This is another game, the graphics are different but the mechanics are suspiciously similar: https://www.coolmathgames.com/0-bouncingballs

Original: http://www.novelgames.com/en/bouncing/

Thank you for telling us about this. Coolmath Games licensed our games to use in their website. They are perfectly legit.

I'm licensing the sound of The Rolling Cube to use in https://notnovelgames2.netlify.com/, bye!

In https://www.youtube.com/watch?v=E05Plnxu1iw they used Novel Games assets in their game and the starting animation is also much faster than in Novel Games. Was that licensed as well?

You probably sued them and their website shut down.

@Piotr Grochowski , it is hard to tell from the video. I tried the link and it is broken, maybe they are already shut down?

They are indeed shut down. Probably you shut them down.