History of Video Games - The First Video Game Ever Made?

As an avid retro-gamer, for quite a long time I've been particularly interested in the history of video games. To be more specific, a subject that I am very passionate about is "Which was the first video game ever made?"... So, I started an exhaustive investigation on this subject (and making this article the first one in a series of articles that will cover in detail all video gaming history). The question was: Which was the first video game ever made?