Its a fair effort but needs some work. First, I'd pick another font from the main menu. Second, I'd fix the typos in the tutorial. Third, it's quite hard to control. The controls should be your focus as the game is frustrating right now. Its just too difficult to fuse with another atom.
With that in mind, I liked the idea and how the game is structured. I understand the slitherio influence, but you did manage to make the idea original enough. There's potential here, but I'd make the control more responsive (I dont mind the small atoms).
I'm sorry, you had such a hard time with the game. you play as an atom floating around in space with only natural forces to control you. It's supposed to be hard to play. It's a time trial that takes practice. The controls are an acquired taste, it may take a few minutes of trying to get better. Hope you can get a high score sometime!