Hey there, good job with the game! Since you asked for it, I'll roast your game (:
At first glance I thought it would be a "letter soup game" and unfortunately it really is. By that I mean that your game art aesthetics isn't similar. There is a lot of shadow in some things, in others flat colors, the font has nothing to do with the game itself. Looks like you have give a piece of paper to everyone in the room and told them to draw something. They did, each pieces are really good separated, but when you put them altogether it is a mess.
But lets critique your specific points:
• Gameplay loop is effective, but not engaging. At first points your game plays well, because it is new and interesting, but it loses effectiveness as it progress due to lack of curiosity. At the round 3 I thought: "Okay that's all I'm going to have there is no point to continue playing it"
• The colors are oversaturated. Looks so intense and bright, unless that is intended I'd suggest to use less saturated colors. Same applies to your Itchio page. I can't even read the link on the description.
• Art style isn't consistent
• Lack of shadow make the player feels floaty. That's okay to add a little bit of shadow below him.
• Melee hit stop players from moving. It ruins the hectic feel of the game. Let him move, there is no difference to it.
• Layer fight on Meteors. At later stages, your meteor/explosion things are overlapping each other, and every time I fire they swap who is in front of what. A bit annoying.
• You don't need to show the countdown every new round, since there is no really time, and it is just unnecessary stuff on screen. Use screen wisely. A new round is good to know, but the countdown each time can be teach to the player organically. As soon as he sees a new round he'll know that there is a break of almost 3 seconds to he breath.
• Melee is bad. At least there is no point that I've could find to use it wisely. If I use, I take damage, if I get hit I take damage too.
• There is no point on the grenade. It will explode and consume gameplay space even if I destroy it or not. It could be used as a counterflow item, if you keep shooting at a shadow dropping it will explode, if not it will not consume your map space.
• Spawn points felt it had some default places after sometime playing it, if they are not random it would be a nice touch.
• Lack replayability, since your game is only this, I miss something to keep me playing. Powerups, different enemies, multiple kills, item interactions. I know it's a jam, but I'm not judging you from what you did, but what you could do.
• The font is hard to read as well, maybe adding an outline/stroke would make it better, but the style isn't consistent.
I've quit at round 10. Hope my feedback can be useful to you.
In case you continue to develop your game let me know! I'd love to see your progress, my info is on my LD profile.