First, congratulation for implementing portals !
In term of gameplay, why do you choose 15 cubes, not 10 nor 5 ? or 10 shot ? ... It must have a reason.
With maximum 3 times of the same sequence the game will be more dynamic.
I see you put a lot of content, and that's great !
Jump sound can be better, but music score is really good.
Nice work.
Suggestion: use doors that open/close automatically to guaranty that player do not forget to close them.