A gap year could make a great difference for your son.
Particle systems are great fun. They’re magic, sort of, in that it’s so easy to compute something that seems like it would be difficult. But do make sure with Penn that your son would be allowed to take the class during his gap year.
@sbjdorlo - I responded to you. I am not sure you received it. I still don’t know how to manage inbox.
I’d go with Penn, because student support is extensive there. Check with the office of disabilities - but UC’s simply can’t compete (they don’t even have money for 1st.2nd year students to have personal/individual advisers). He won’t be living at home, so what you need is the most thorough support network with everything in place to help him.
Check the UPenn catalog to see if there are different versions of calculus (ie., calculus for engineering, calculus for business, etc.) and see whether there are classes where he’d be in a more applied setting.
The video game industry is bigger than all other media, combined.
Just to follow up and close out the thread, my son did choose Penn and will be taking a gap year. He actually might get an A in calculus this semester! 
And he decided that he likes his Java class better than animation, so who knows what major he’ll end up in.
That is great to hear on all counts. Congratulations~