I'm playing online. I encounter these 'Missing No.' people whose names are just missing characters. The squares, if you've seen them. Yet when the game starts, it just ends, because it doesn't recognize these people. It's really weird, but it serves as a method of free XP. As I type, this glitch is still going, and I'm just earning a lot of free XP and cash.
Normally , when this happens to me, there are still opponents to play against
A few people are "mising no" characters, but then there are a few "real" players. the missing no characters never leave. Since i've never been in a lobby where there aren't any real players, I couldnt say anything about the XP/game ending parts.