The engine for the my own train was available in 8 configurations.
Large and Small, and then 4 different colors for each type (Blue, Green, Black, Brown). The engines were mostly black with the color you could choose being the accent. They came unmotorized but as you can see were set up so you could fairly easy convert.
Your bundle includes a couple of the cars you could buy individually for the series as well. There was also a passenger car and a caboose.
At the time it was considered a big deal if I remember correctly because of the the options available. Made it good for train fans but also people were hoping it was signalling a new era of customizable sets.