Rare Star Wars - Lego "Mindstorms" Droid Developer Kit (1999) [PC-Windows Lego Construction Set (with CD)].
The droid developer kit lets you make hundreds of your own droids, like a moving R2-D2, with LEGO parts and instructions. Came with Micro-Scout controller (the brain) with a built-in motor and light sensor.
A Great Star Wars Collectibles.
I bought this from Metro in 1999 for S$229. Tried to play with my 10-year-old daughter then to interest her in computer without much success. Since then, it had been packed into the storeroom until now. Hence, every parts are still available, rather news, including the paper box.