Hi, the game is really cool and it is really impressive for you first game. Since it is your first game I will tell some things that you could have in mind to improve: transitions, music, audio effects, other animations than the own player, chose of colour, particle effects and others. The art is really interesting and I really liked it, you should continue making that!
Things that you could improve specifically on this game: the camera movement on the Y is no smooth and doesnt feel good, other thing you could do is organise the green dots in a symmetrical way, it feels more professional and it looks better.
Good job making your first game ! I gave a big comment because I really want you to improve and I really wanted someone to tell me when I started. Continue with your journey ! Good luck !