Verisimilitude

Is it Believable?
Suspension of disbelief, sought by film makers and authors, allows for immersion in a fictional setting. Your mind temporarily suspends the fact that you are sitting comfortably and allows the story to take you along to exotic, exciting and sometimes scary places - a "you are there" experience - to identify with a fictional character, to worry about the character, to share in the triumphs and heartbreaks of the character almost as if they are real. This is verisimilitude, to feel like something is true and it can be a goal in roleplaying.
White Box is a game. The Last of the Mohicans is a novel and Gone with the Wind is a film. But they all can be a little more. With willingness to put our own lives on hold for a few hours and immerse ourselves in a fictional setting focusing on fictional characters, we can enjoy a mental adventure full of laughs, joys, triumphs and tragedies. Story-telling around the fire, drama, tragedy and comedy of the theater and the singing of the epics are how this form of entertainment began and there continuance through the ages proves our desire human desire for mental imaginings.
So what role does believably play? A joke can make us laugh even though nothing about it seems real. A story about animals that talk and wear clothes can entertain us and even teach us a few lessons (Aesop's Fables). So why escape reality by immersing ourselves in an imaginary setting full of imaginary characters and imaginary danger? White Box is a game and it can be played just like other games, moving pieces about measuring inches, rolling dice, etc. But it can also be so much more.
Before I discovered White Box, I played other traditional tabletop games and many "wargames". Some of the "wargames" were advertised as "time machines" - a simulation that could transport the player back in time and put you in command during an historic battle so that your decisions affect the outcome. Perhaps because of this wargame experience, I sometimes think of fantasy RPGs as "transporters" to a time that never was, but could be, to a fantastic world of adventure where I get to make the decisions. Verisimilitude is very important in such an imagined experience.
At the end of the day, it's still just a game - something we do for fun and entertainment. The experience, shared among friends is real, however. Like most in this hobby, I have great memories of games past, shared among the best of friends. Making the adventure seem real in the moment can enhance everyone's fun and heighten the strength of the memories.