Whoah!
Siege of the Citadel was my third major nerd game, acquired in a Walmart in 1994. My mother wanted to buy me something to make up for the fact that we had just moved far away from the place I’d lived for the previous 5 years, which was the longest we’d lived in one place in my entire life. We would move from there after a year, and eventually my little brother would get into the box and lose several of the pieces.
The idea of co-op play, characters that persisted through missions… The whole boardgame with RPG elements shtick. It really stuck with me. I’d played, but never owned Heroquest before that, and the idea of something that would stand up to a lot of repeat play was a real selling feature.