In terms of games we're almost 100 percent, absolutely positive will never escape Japan Captain Rainbow is very nearly at the top.
Despite being about a washed up, long-time superhero character Captain Rainbow isn't actually a direct sequel to anything. The titular captain has only appeared in one game to date. However, the rest of the game seems clearly set in the greater Nintendo milieu with characters from Mario, Zelda, Punch-Out, Chibi-Robo, and more, increasingly obscure series.
Being developed by skip Ltd., and written by Kenichi Nishi (Super Mario RPG, Incredible Crisis) Captain Rainbow is... weird. Ostensibly the game is about the super-heroic Nick -- a.k.a. Captain Rainbow -- fulfilling the wishes of forgotten Nintendo characters. In practice it almost seems to be poking fun at the family friendly nature of its own publisher's games.
There are entire side stories about helping a samurai overcome his fear of large breasts, Birdo's gender "controversy," and a golf player who can't stop scratching his balls (which he keeps down his pants).
It's absolutely the sort of thing that would play well with a specific crowd. However, that crowd isn't likely made up of retirement home dwellers and 10-year-olds. That is to say, the majority of the Nintendo Wii market, which is the console where Captain Rainbow was released. It was, predictably, a massive financial failure. Barely more than a 20,000 copies were sold the last time that anyone checked (a veritable smash hit for most Wii games without "sports" in the title, mind).
Sadly, given the game's failure it seems unlikely Nintendo will even consider backing another game of Captain Rainbow's kind anytime soon, much less localize the original for English speakers.