Fortnite’s mysterious cube keeps moving, and I can’t stop following it

Last night, not long after I put my kids to bed, I made some coffee and turned on my PS4 to play Fortnite. It wouldn’t have made the best spectator experience: I sat perched on an in-game cliff for several minutes, barely moving. I wasn’t playing stealthily, trying to avoid detection from other players. I wasn’t even armed. Instead, I was staring intently at a giant purple cube, hoping it would move. Five minutes into the match — in which I somehow remained unharmed &mda