Hi yrbiax,
Thank you for trying my game and the feedback. In regards to the enemies, thank you for letting me know you'd like the game to be more challenging. It wouldn't be a problem to have them cover more ground or add more. As far as the game going to the main menu when retry is hit, I can understand why you say that. I can change that. As far as sound effects, I'm not totally sure how to do that but there is a tutorial on how to add sound and music I can look at to see how.