Whizbang Dustyboots
Gnometown Hero
Boot Hill, despite TSR pushing it pretty hard, never took off. Neither did competing products throughout the 1980s. It took adding fantasy and horror into Westerns in 1990s for games like Deadlands and the Wild West setting for Werewolf to succeed.While a wild west or sci-fi game might have still taken off (spaghetti westerns were still going strong then, sci-fi had its own hardcore fandom), people were very much primed to step into a fantastical world.
If Boot Hill had been the first RPG, I don't think it would have experienced anything like the success D&D did.