I like the artstyle.
The particles fit the galaxy environment and I like how they suround the bigger particles.
The music is great and gives good vibes.
The theme "Stronger Together" fits your game very well.
If i got it right, then the goal in your game is to combine as many particles as possible without destroying it. But I don't really see a reason for it.
It would be cool if you would have a little collection menu where you can see all the diffrent types of combinations you can do and which one of these you already had.
That way you would have a small goal of trying out all these variations of combining particles.
A little mainmenu might have been nice to have.
In the mainmenu you could then also add a little library of the diffrent types of particles.
I hope this little feedback was usefull and I wish you a lot of fun creating games in the future.
(and sry that I'm not very good at writing feedback o.o)