cribbles

Yes. I use and enthusiastically endorse Math Academy. It is far and away the best self-learning educational resource I have ever tried; leagues better than Khan Academy.

I'm a self-motivated adult learner, so I don't know what it's like for kids. Though the program was originally designed for them, so I suspect their experience would broadly be similar to mine.

As other commenters have mentioned, you need to be okay with grinding through problem sets with no videos or UI pizzazz -- maybe this doesn't work for everybody. I'd compare it to the difference between trying to learn a language through scattered YouTube videos and Duolingo versus tandem and grinding on a good Anki set.

NB: I'm taking it for the Math for ML track and am currently most of the way through the Math Foundations III course. So I can only comment on the lower level courses.

> the scene is moving towards Leipzig

Speaking as someone who's split ~half my time between Leipzig and Berlin for the last 5 years, this is not true.

Leipzig's club scene is an extension of its university population. It's younger, straighter, whiter, and about two orders of magnitude smaller. People visit the clubs while they're going to school there, then they graduate and move elsewhere. Often to Berlin.

Why does this illusion exist? Because Leipzig is about an hour away from Berlin by train. Berliners visit for a weekend and think "wow, it's like Berlin in the 90s! Still cheap! And look at all these cool young kids at these scrappy clubs -- so that's where the underground has gone!". Then they go back to Berlin and spread the word to credulous out-of-towners, who go on to repeat this truism to people who have never visited either city.

In reality, Berlin's club scene -- both "mainstream" and "underground" -- dwarfs that of any other city. Nothing short of an asteroid hit is likely to change that.