Hello there!
Yep, I pressed X and aimed for the "PLAY !" 🎉 Right when you start the game, there is a big "Press X" on the lower (maybe middle) left of the screen, besides, you've got all the information on the game page https://loupswann.itch.io/gravity-chaos-browser
I'm on level 4, for now 😅
Well done LouSwann 👍