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"
I don't think it is unreasonable to define a "video game" as one employing video graphics and real time input. Things like Tennis for Two (and the later Spacewar) are clearly video games in a sense that mere simulations of board games are not.
I built a basic version of Tennis for Two a while back, using regular op amps. Some modern oscilloscopes have bad X-Y mode implementations, but most non-extremely-cheap scopes are probably decent enough. https://blog.qiqitori.com/2024/08/implementing-tennis-for-tw...
I'm also planning on selling a kit in the near future!
See also Wikipedia's overview: https://en.wikipedia.org/wiki/Early_history_of_video_games
If you want Tennis for Two (1958) to be first, you have to introduce criteria that excludes OXO (1952), Checkers (1952), and Sheep and Gates (1952)
I'm also planning on selling a kit in the near future!