As i said in my post, it depends on your definitions for the game, i put space war as it was if i remember right, the first one designed behind the idea of being a "game", tennis for two was a test to see if something like that could be done and pong was probably the first commercially available video game hence why what's defined as first depends on how you define it.This was what I've known to be one of the first if not the very first "Video Game" for the longest time.
I should point out that there is a good amount of the industry that considers pinball with digital scoring as the first video game, and it's much older than all these options.