Hello, I'm 19 currently second year in college, After one quarter of taking on many math/science classes and struggling in them, I've realized how my knowledge is both shallow and fragile, even in the subjects I've already learned. I currently wish to reestablish my knowledge from the ground up, especially in mathematics and would like some recommendation for good textbooks from which to use for self learning. I would like enough textbooks to be able to have an intuitive understanding (like that of Feynman's), as well as a complete understanding (as I've heard of Spivak's Calculus book). Additionally, I like to play games (everything is a game with the right perspective!) so it would be helpful to set up the learning like some sort of game with objectives. That is, I want to know how I can be self-assured that I have mastered a certain material. I think the biggest problems in learning (self learning specifically) are you don't know what you don't know and you don't know if what you do know is wrong!