"What other old school game should have become as big as D&D but didn’t? Why do you think so?"
To be honest, as a new inductee to the RPG genre, I haven't had the experience with older RPGs that many of my contemporary bloggers have; however, the above question doesn't specify old school roleplaying game- it just says game.
And so I'm calling back to my childhood and HeroQuest.
HeroQuest is basically the reason I'm into roleplaying games today. It featured adventurers delving into dungeons and ruined keeps to accomplish simple quests and escape with loot. Characters were carried over, and each player received a character sheet for their trouble, so I naturally spent every second I wasn't playing HeroQuest reading through the DM's booklet and checking out equipment tables, magic spells, and dungeon setups.
Looking back, I probably spent more time learning how to play HeroQuest than actually playing it, and looking for it today on Amazon makes me sad it never saw a larger audience, because there's no way in hell I'm paying 400 bucks for it now.
I think the reason HeroQuest failed was because it was filling a niche that didn't really need any more filling. Anyone who was interested in playing that type of game was probably already playing D&D, and therefore didn't really see the point in dumbing down their experience. Hopefully a good number of people used it as a springboard for their eventual run in tabletop RPGs, but at the time of its release, when someone said 'board game', everyone else thought Monopoly. Which sucks.
Monopoly sucks, guys.