Programming memories

I loved programming as a kid (still do and still am). Some of the hobby projects I remember:

• Gravity & planetary motion simulator. The generated trajectories were interesting. Programmed, as many other projects, in Flash / ActionScript (RIP this beautiful programming environment).
• Weierstrass function plotter. I was fascinated by this function that was continuous everywhere, but nowhere differentiable. With this app you could zoom in infinitely close on the function (or at least until the edge of numerical floating point precision).
• Fractal tree generator (including a clumsily animated giraffe roaming between the trees).
• PID controller for a two-wheeled balancing robot (like a Segway) made with Lego Mindstorms.
• A chess AI. (Prototype in Python, final optimised code in C, using vectorized CPU instructions).
• A Scrabble AI (directly interfacing with the Wordfeud API).