I actually have a lot of criticisms to provide:

• the more you get hit, the bigger you get, this means it's easier for you to get hit again, you have to think that if the player is taking damange, getting bigger means it's easier to take more damage, so the worse you play, the harder it gets, which is not a good system to have in the game as it disincentivizes the player on getting better
• I can shoot as fast as I can click my mouse, which is not good, if you are not gonna limit the rate of the gun, you might as well make it be a machine gun and make the gun keep firing if we keep the button pressed, otherwise, the only think I will gain from playing the game is tendinitis from rapid-repetitive clicks
• I don't link that it's quite unclear how much bigger the enemy will get when I shoot it, think about it: when a enemy gets close, I have no choice but to shoot it, but shooting it will make it bigger which will lead to me taking damage which is not good. A better system would be: if the player is not shooting the gun, you run faster than when you are shooting, so when an enemy gets too close I can make a decision on whether I should shoot or run to prevent the damage I would take
• I also don't like how the game has no end to it, you have a gameplay loop, but the score is only limited by how much time I wanna keep playing, if you add a time limit to the game, or instead of getting -30 points you just die, I think it would lead to a game that is more fun to play/compete.
• also, I don't like that the enemies spawn without time for me to react to their spawns, they appear on the edge of the screen, but they run so fast that I don't have much time to react to them, I think it would be better if they were, either slower, as it would leave me time to react to ther spawn, or if the screen would warn me a second before they actually spawn so that the player can have the sensation that there are more skill on the play instead of blaming bad RNG of receiving a hit when you are just running from a red eye.
• also, instead of letting the eyes get bigger on hit, you could make they grow based on time of their existance, that way we can teach the player that if they let the eye exist for too long, it will just get bigger and bigger which would make it both easier to hit to amend the problem the player has created for themselves, but also it incentivises the player to try to get rid of the enemy as soon as possible to control their threat

despite the several criticisms I had, I had fun playing it, got a score of 236 before realising the game would have no ending and my hand was already several clicks away from being tired, so I just stopped  

All the pieces are there, but I just couldn't get the hang of this game.  It might just be a "git gud" issue but for me the enemies were either coming in too fast or tanking too many hits and I just couldn't get out of the negative scores lol.  My only note would be maybe dial back the speed and hits and add some evasive movements to keep the game challenging but a little less overwhelming.  Still it worked well and it is for sure the groundwork of a good "asteroids" style game.