Uniqueness and Theme: Unfortunately had to 1-star both since this is a pretty general incremental game applied to chemistry.
Balance: Not great, not terrible- It is quite linear though (Literally) which makes things feel a bit... Odd? It's pretty short and fast paced anyway so nothing big here.
Fun: Was a nice time killer, like someone else already pointed out. I envy anyone who can make something this coherent in Scratch.