Ok I'll try to give a real in-depth review of this game. 

      First off, I absolutely LOVE the choice of music you used. It really suits the assets used in this game and the idea behind it. Plus, I really love listening to music like this its just peaceful and relaxing so I'll tip my hats off to that. It would of been a really good theme for "You" if you actually planned on creating this based on an aspect of yourself. 

       Second,  the idea and concept behind this is not bad at all! You give me a slight challenge by having me try and bounce shots off a mirror onto trees instead of doing it directly, which I kind of found pretty nice and a bit enjoyable!

        Now, for a bit of problems I found, heres what I feel:

• I ended up falling off of the island. Maybe consider adding colliders on certain areas of it so the player doesn't fall or add a spawner below so I can teleport right back to the island.
• The crosshair aim in the middle kind of has no use seeing that the shots shoot at a certain angle and doesn't change directory based on the position of the crosshair.  It would take a bit of scripting to get it to function like that , but just having that mobility of the shots would make things look more realistic. :D
• I feel the mouse sensitivity was too fast. Maybe consider giving the players an option to setting their sensitivity or set it to a general speed where it's suitable for almost everyone.

        Now for a suggestion I have:

• I thank you for doing a browser version by the way, as I run on MAC. There is an option when editing your game and uploading a browser version where you can add a fullscreen button and also change the size of the browser screen too so you can fiddle around with those :D

Overall, for a first game, this was seemingly enjoyable! The music and assets stood out to me the most because it's colorful and vivid! Also, the bouncing was pretty nice and realistic, so I don't really have much to say about that. Nice game! With a bit of polishing, I know it can be better!

One thing to note: you can set the canvas size of your game to be automatic, since its a Unity game. Usually, Unity provides a full-screen button at the bottom right-hand corner, but because you set the canvas size to be small, it is not accessible. That being said, well done with your first game jam game!