Hey there. I gave your game a shot. Here are some thoughts:

• It would greatly benefit from having a cursor on screen. It was hard to tell were my shots were heading because the character is off center and the bullets go at an angle toward the center of the screen, which I wasn't expecting.
• I'm kind of confused as to why I'm a bottle. I'm really small, which makes it harder to tell where I am when there's a lot of enemies on screen.
• You might want to think about making the earlier enemies fade away after a while. Very quickly, the game started chugging because there were literally thousands of enemies on screen.
• A typical issue with games like this is the player will naturally move backwards and in a circle unless there is some force incentivizing them against doing so. Having some kind of forward attack would be beneficial because 1) It would incentivize them to move in a direction that isn't backwards 2) blasting through hundreds of enemies would be fun 3) it would provide a logical way for the player to get any presents that might be stuck in a horde of enemies.
• You might also consider adding logic to the enemies to prevent them from lumping together. Also, increasing the size of the playable area might be beneficial. Having more "zones" to move around to and from would add the possibility for more strategy.

Overall, I thought it was fun! I hope you get some insight out of what I said. I also have a game you could try if you have a minute. Have a good one!