mana in games, and why it's blue

Something called "mana" is used frequently in computer fantasy games, but why is it called that? Why is it always depicted as something with a dark blue color? I don't know the history of the word, but this YouTube video asks these questions and tries to answer them.

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I can't vouch for its etymological accuracy, but I played lots of hours of 3 video games that it mentions as having pivotal influence in this trend. The first was Dungeon Master (1987) on an Amiga, then Warcraft 2 (1995) and Diablo 1 (1997) on pc. These are all important titles in the genre, so I grew up immersed with "mana" as the fuel for magic, and it was always blue in color.