This is nearly exactly my dream rewrite of my iOS app Mindscope http://www.mindscopeapp.com/ that I never quite got around to doing. Love this. Congrats!

Mindscope always was text (and later arrows) only, which had its advantages because it forced focus. But I love the Apple Pencil support!

I love seeing your solutions to the same problems I encountered developing Mindscope. Especially Love your solution for dragging one card into another by dragging it then pinching into the other. It feels very natural.

Major props.