Ask HN: Advanced free math courses online with exercises?

I wonder if someone can help me find free math courses online that comes with exercises? I have been going through all the math courses Khan Academy offers, https://www.khanacademy.org/, but their material ends with basic calculus so going beyond that the site is of no help. I appreciate sites that tracks your progress and has lots of statistics and points you can score. Even simple sound effects when you get answers right is something that makes a big difference in how fun the site is to use. Are there any such sites? I don't care much about the video content as long as it has exercises organized in some way. Right now the topic I'm learning is abstract algebra but I'm also trying to find online exercises for other advanced math topics. I.e I want something exactly like Khan Academy but more advanced.