The "hacker" community around Mindstorms was huge in the 00's. After the RCX was reverse engineered, all sorts of language support appeared. BrickOS for C and C++, lejos for Java, NQC, etc. I bumped into lejos in a section on Mindstorms toolchain options for Macintosh in one of my dad's MacWorld magazines. He helped me set it up and that's where I started learning Java.
It was a life altering gift for me if there ever was one. The first large event that set me on my current path.
I honestly kind of miss the silly hacker/spy/matrix-y aesthetic of computing in the early 00's. It was fun when I realized those LEGO Spybotics kits could be targeted by some of the Mindstorms tools. Everyone in elementary school thought I was going to be an evil genius. Now I build storage virtualization systems. Oh well I guess.