I added your video to the playlist.
Thank you for your comment. I agree with what you said. The speed must be topped. My idea is to create new obstacles for my game (not just asteroids) that will appear at some point (with different mechanics) to increase the difficulty. As long as those obstacles are not implemented, this speed mechanism make sure everyone dies at some point ^^. I will continue to develop this game in the future, but I like to work on other projects too. (And unfortunately, my spare time is limited...)
(Congratulation, I think you even beaten my own score)