Here's some feedback on your game:
1. Theme
The idea is really funny, and it fits the theme well, but unfortanetly not too creative, so 4/5.
2. Gameplay
The game is really, really polished. The shooting feels amazing with the sound effects and particles and everything. It's addicting, but has some major problems: First of all, you can't die, which makes it way too easy. Also, you have too much time when the cousins get to your computer. Plus, aiming would be nice, because just holding down the spacebar gets kinda boring after a while. And you designed this huge, beautiful map, but basically you just stand on your computer all the time, so maybe make things on the map you have to collect or drinks and food you have to get for regeneration. Also, shooting your cousins is a bit...welll, i think you see the problem here XD. Maybe just make it so you have to push them out of your room with your projectiles.
3. Graphics
Whoever made the art is clearly really talented. The lighting and artstyle and everything is perfect, but while the colorful particles look amazing, i would make a seperate sprite for it, cuase they look kinda bland compared to the other stuff.
4. Sound
The music is not bad, nothing memorable, but fits the game and the sound effect really add some more fun and make the game more addictive. Good job on that!
I hope my feedback helped you a bit, and if you have time, it would be really nice if you could check out our submission too. Thanks! :)