Ok, I went to this yesterday and I have to say, if you really get into it you can actually believe you're in a true game like in 999/VLR. You even get to wear the watches and use them to open several doors. (And while there was a puzzle involving addition of the numbers on the watches, there was nothing on digital roots, sadly)
While I won't divulge much, I should say that there is a very good reason Clover is on the poster. Plus, there's a lot of neat easter eggs scattered in the escape room that link back to the game.
The only real issue I had with it is that in our escape, one of the teams discovered that their puzzle was more-or-less solved and left the rest of us for dead until the game master informed them that, yes, you still have to help the rest of us who are solving it the good old fashioned way. (ie do the human version of tapping every part of the screen and see if there's an answer there)