I had an old RS Color as well, but I didn't actually build that one..
Yeah you are right.
However to clarify, in my mind it was a build.
I needed to control an analyze Data involving Human reaction to various Visual and Verbal stimuli.
These little thingie (Color Computer) had an Analog to Digital Converter at the Game port input. I.e., it took Analog input (variable resistance, or low voltage changes) and changed them to Digital variables that can be used with the appropriate Apps to analyze reactions.
So I built an elaborate system that presented variety of commands to the Subjects and boxes that where hooked to the game port and provides outside input to be processed for research.
32 years old sample from that time.
Rest a sure that Humanity was better served by the scientific outcome of this builds than from the thousands of self build game Computers that are used for make believe Killing game.