I dont think Shenmue is to much for the mainstream audience. Shenmue is just a unique franchise completely different than any other game. Shenmue is a game ahead of its time.
I wanted to say, Shenmue was mainstream when it was released for the SEGA Dreamcast
but for that audience, much like Virtua Fighter was for SEGA fans and then players who moved to PS2
Virtua never reached a wider audience like Tekken
Silent Hill never reached a wider audience like Resident Evil
No One Lives Forever never reached a wider audience like Half-Life
and Shenmue never reached an audience as big as Yakuza
all these have something in common
Shenmue shares a lot with No One Lives Forever in terms of marketing and release time
NOLF was stuck in PC with high requirements and it received a broken port for the PS2 years later, despite winning several game of the year awards when it was released in 2000, it remained relatively unknown to the big public compared to other first person shooters
today its a hidden gem, like Shenmue
Shenmue had the lucky of coming back, NOLF and its sequel are stuck in copyright hell, the only hope is Microsoft purchase Activision and they partner with WB Games to release the games again for the XBOX
Shenmue is like an indie game now, I want to say being a superb product is not enough if your marketing strategy sucks, NOLF and SHENMUE were victims of their time
and NOLF1 is a hell of a good game, I think today Shenmue is my favourite, but NOLF was my favourite for over 20 years , sadly it was also a commercial failure
(the main characters also ride motorcycles lol)