What should I work on this weekend? (Patreon)

I'm afraid this pool would end up getting one or two votes and proves I'm still the least popular kid around, but there is no way around it.
As promised, my weekends belongs to my patreons now, and I need your opinion on how should I spend it.
I have few relatively difficult problems in mind that I wanted to tackle for a while but I didn't really had enough time for them, but now, I can throw weekends at them till they're done or I'm done with them. here's a list in no particular order, choose the one you want to see first.