I have absolutely no idea. For me this question is akin to asking what is the first movie you saw, song you heard, tv show you watched, book you read, etc. Videogames have always been there and I have always played them. I can make the educated guess that it was something for the Atari or Commodore 64. Which version of the Atari or which game would largely be up to my parents recollection and they don't remember that stuff. They didn't keep the Atari and I only have some vague memory of it and I played the C64 for years.

I imagine that people about a decade or so younger than I view this question in the same way I do. Being around videogames and computers is just an ubiquitous part of life (even more so for kids growing up today) and I had that same feeling growing up. Always had a computer and videogames around. I am 32 which makes me somewhat different as that was definitely not the norm in the early to mid 80s.