Thanks to a comment by redditor u/Responsible-Draw5354 and some research on my side I've got a story to tell.
It all begins in the year 2010 ...
2010 - Jason Sondoh releases "Escape of the Dead": https://boardgamegeek.com/boardgame/87632/escape-dead-minigame
2020 - Pascal Toupy takes the mechanics of "Escape of the Dead" and releases the game in some wargaming magazine as "Firebase Vietnam": https://boardgamegeek.com/boardgame/324602/firebase-vietnam
2021 - Brendan Whyte creates "Defense of Rorke's Drift" and attributes his game to "Firebase Vietnam": https://boardgamegeek.com/boardgame/338157/defence-rorkes-drift
2022 - I am introduced to "Defense of Rorke's Drift" without being aware of all the other iterations and think "Hey - his would make some cool Zombie game": https://catzeyeshq.blogspot.com/2022/11/braaaaainz-quick-zombie-defense-game.html
Ladies and Gentlemen - the circle of life.
p.s.: If anyone of you is active at the 'geek and wants to earn some Geekgold, you are free to create a game page for BRAAAINZ if you assign it to my designer's page: https://boardgamegeek.com/boardgamedesigner/12247/kai-bettzieche (which is still in place, oddly enough..)
In a second step you might want to create a "is reimplemented by" loop:
Escape of the Dead -> Firebase Vietnam -> Defense of Rourke's Drift -> BRAAAAAINZ -> Escape of the Dead
Just for "teh lulz"
Best regards (also to the crowd at the 'Geek),