Yeah, certainly one of the first, I'd agree with that. First I'd ever heard about it was in the documentary Thumb Candy, at the beginning Steve Russell gives an introduction to Spacewar!, which is quite fun to see:
Digging around, I found even more early examples of computer-based games that appear to have been largely overlooked, I certainly don't remember hearing about them before, seems like the first video games may have emerged in the early 50s (between 1950 to 1951, depending on whether it needed to be on a general purpose computer):
However, whilst I respect it's open for interpretation, I would say the first video game was Tennis for Two.
https://en.m.wikipedia.org/wiki/Tennis_for_Two
There's also OXO, which predates both Spacewar! and Tennis for Two:
https://en.m.wikipedia.org/wiki/OXO