As per the conclusions of that great video, going back before Pong and defining a "first" video game depends heavily on your definition of both "video" and "game"<p>See also Wikipedia's overview:
<a href="https://en.wikipedia.org/wiki/Early_history_of_video_games" rel="nofollow">https://en.wikipedia.org/wiki/Early_history_of_video_games</a><p>If you want <i>Tennis for Two</i> (1958) to be first, you have to introduce criteria that excludes
<i>OXO</i> (1952), <i>Checkers</i> (1952), and <i>Sheep and Gates</i> (1952)